Ultrafine-grained cemented carbide is the main material for manufacturing micro drills used on printed circuit boards (PCBs). Cobalt content in cemented carbides is an important parameter that affects their mechanical properties. Three types of ultrafine-grained carbide micro drills with different cobalt contents and an average grain size of 0.3 µm were prepared. They had the same structural design, with a diameter of 0.3 mm and a flute length of 5.0 mm. The performance of the three types of micro drills in drilling a high Tg (Glass Transition Temperature) PCB under six sets of drilling parameters was tested and evaluated from the aspects of wear, hole position accuracy, and hole wall quality. The results show that lower cobalt content indicates smaller micro drill wear and higher hole position accuracy. The cobalt content has no significant impact on hole wall quality. Appropriately increasing the feed speed will help reduce micro drill wear and improve drilling quality. Excessive feed speed will lead to chipping of cutting edges and serious deterioration of hole wall quality. In general, the 0.3 mm diameter carbide micro drill with a cobalt content of 6% and an average grain size of 0.3 µm has the best drilling performance.

The powder properties, pressing properties, microstructure and properties of WC-8%Co-0.4%VC ultrafine cemented carbide mixture prepared by three groups of slurries with different solid contents were studied. The results show that with the decrease in the solid content of the mixture, the content of fine powder in the mixture increases, and the degree of particle breakage increases. The loose density of the mixture gradually decreases from 3.4 g/cm3 to 2.5 g/cm3 , and the fluidity gradually deteriorates from 32 s to 39 s; the pressing pressure of the mixture PS21 increases from 2 250 N to 4 050 N, and the green compact strength decreases from 5.52 MPa to 2.88 MPa. The decrease in the solid content of the mixture leads to the gradual decrease in the average size and maximum size of vanadium-containing particles in the mixture, from 1.085 µm to 0.523 µm and from 1.627 µm to 0.876 µm, respectively. With the decrease in the solid content of the mixture, the uniformity of the cobalt phase in the alloy gradually decreases. When the solid content is as low as 57%, a cobalt pool of more than 1 µm will be formed, which will reduce the bending strength of the alloy. When the solid content is 64%, the alloy has a uniform distribution of WC grains and cobalt phase at the same time, and the bending strength is the highest, reaching 2 780 MPa. Therefore, adjusting the solid content of the mixture reasonably can effectively control the comprehensive mechanical properties of the alloy.

Nanocrystalline binderless cemented carbides were prepared by traditional powder metallurgy process through vacuum high-temperature sintering and vacuum pre-sintering + hot isostatic pressing. The effects of sintering temperature and sintering pressure on the microstructure and mechanical properties of the cemented carbides were studied by Vickers hardness tester, scanning electron microscope, and wet grinding wheel wear tester. The results show that increasing the sintering temperature leads to abnormal grain growth in the cemented carbides, and increasing the sintering pressure results in a high-density and uniform microstructure. The nanocrystalline binderless cemented carbide prepared by vacuum pre-sintering + hot isostatic pressing has excellent mechanical properties. The hardness is 29.01 GPa; the fracture toughness is 8.2 MPa·m1/2 , and the abrasive wear value is 0.06 cm3 /(105 ·r).

In the forming process of cemented carbide cutting blades, the quality of powder filling in the mold cavity will directly affect the quality of the molded parts. Realizing the dense filling of powder in the mold cavity is the key to improving the quality of powder metallurgy products. In this paper, the filling process of the mold cavity during the preparation of cemented carbide cutting blades was studied by the discrete element method (DEM), and ready-to-press (RTP) materials were used as the research object. The DEM models of RTP particles and the power distribution process were established. The powder distribution process was divided into two stages: blanking and particle filling. The packing density and particle segregation were taken as the evaluation indexes for the powder distribution quality inside the mold cavity. The influence of the physical properties of the powder, the geometric structure of the cavity, and the powder distribution technology on the powder distribution effect was analyzed. The results demonstrate that the particle distribution coefficient, the insertion ratio of the feed tube, and the translation speed of the filling shoe are pivotal factors influencing the packing density of the powder within the mold cavity. Specifically, when the particle distribution coefficient (n) is set to 0.5; the insertion ratio of the feed tube is 50%, and the translation speed of the filling shoe is 100 mm/ s, an optimal particle packing density is achieved. By optimizing the key parameters derived from simulation results, the powder distribution effect is enhanced, offering guidance for practical production.

The influence of tool coatings on the processing performance of 6063 aluminum alloy and aluminum substrate, as well as typical aluminum-based materials, was studied. The friction coefficient of aluminum alloy with different coatings was studied by using a friction and wear testing machine, and the morphology and composition of the wear scars on the surface of the grinding pairs were analyzed. Different kinds of coated drill bits and routers were designed to machine 6063 aluminum alloy plate and 5052 aluminum substrate. Through the testing of drilling and routing performance and the evaluation of machining quality, the processing difficulties and tool failure mechanism of aluminum alloy during drilling and routing were analyzed, and the solutions to high quality and long life for processing typical aluminum-based materials used in consumer electronics and electronic circuits were obtained. The results show that the minimum friction coefficient of hydrogen-free diamond-like coating is about 0.06; the friction coefficient of carbon-based composite coating is about 0.15, and the friction coefficients of cemented carbide, TiSi-based coating, and TiAl-based coating are all greater than 0.6. Hydrogen-free diamond-like coating can effectively inhibit the adhesion of aluminum chips on the drill bits and router, improve the chip removal ability of the tool, and keep the cutting edge sharp during machining. During the drilling process, the problems of the broken micro drill bits, a large amount of burrs on the surface of the hole, and short tool life are solved. Compared with uncoated cemented carbide micro drill bits, the life of the drills is increased by three times. During the routing process, a large amount of burrs on the surface of the slot and poor dimensional stability are solved. After routing an aluminum substrate of 10 m, excellent dimensional accuracy can still be obtained.

The chemical vapor deposition (CVD) Al2O3 coating possesses high hardness, good toughness, as well as excellent wear resistance, heat resistance, oxidation resistance, and chemical stability. It is a cutting tool coating material with excellent comprehensive properties. In this paper, the MT-TiCN /Al2O3 / TiN coatings with (104), (0012), and (012) texture orientations of α -Al2O3 were prepared by CVD. The microstructures, texture orientations, and coating properties were studied by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The experimental results show that the columnar grains of the α-Al2O3 coating with high (0012) texture orientation are more complete. The texture orientation of the α-Al2O3 coating will affect the morphology and texture orientation of the surface TiN. The surface TiN of the α-Al2O3 coating with a high (0012) texture orientation exhibits a high (111) texture orientation. The surface TiN of the α -Al2O3 coating with a (104) texture orientation shows a weak (111) + (331) mixed texture orientation. The surface TiN of the α-Al2O3 coating with a (012) texture orientation presents a weak (220) + (420) mixed texture orientation. The results of the cutting experiment on 42CrMo indicate that the wear resistance of the α-Al2O3 coating with a high (0012) texture orientation is superior to that of the coatings with (104) and (012) texture orientations, mainly manifested in that both the rake face and the flank face of the α-Al2O3 coating with a high (0012) texture orientation have better wear resistance.

Ti(C,N)-based cermet was prepared by high temperature and low pressure sintering in Ar + N2 atmosphere with submicron Ti(C,N), different kinds of ultrafine carbides, ultrafine Co powder, and Ni powder as raw materials. The phase composition and microstructure of Ti(C, N) - based cermet were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The Vickers hardness and fracture toughness of the specimens were calculated by the Vickers hardness tester. The results show that the sintering temperature is slightly higher than the traditional temperature due to the increase in the types of carbide components. When the sintering temperature is 1 470 °C, the microstructure distribution of the cermet is uniform, and there is no obvious grain growth. The phase only have (Ti,M)(C,N) (M = W, Mo, Nb, and Ta) solid solution phase and Co + Ni bonding phase. At this time, the hardness and fracture toughness of the specimens match the best (1 730HV10 and 8.02 MPa ∙ m1/2 ). Through the optimization of the sintering process, the cooperative regulation of microstructure and mechanical properties is realized.

Selective laser melting (SLM) technology is currently one of the primary processes for additive manufacturing of WC-Co cemented carbides. However, due to the significant differences in physical properties between the metallic and ceramic phases, obtaining crack-free and pore-free cemented carbide components with high performance through SLM printing remains a significant challenge. This work first investigated the influence of laser power, scanning speed, and hatch spacing on the porosity of the fabricated specimens by using WC-Ti powder, which has a relatively small difference in melting points. On this basis, a function relationship between laser process parameters and the density of the printed parts was established. It was found that the scanning speed had the most significant impact on the density of the fabricated specimens. Moreover, by further synergistically optimizing the laser spot size and powder particle size, the porosity of SLM-printed WC-Co cemented carbides was reduced to 1.5%, and cracks were eliminated. Molecular dynamics simulations were employed to reveal the mechanism by which the optimized matching of laser spot size and powder particle size inhibited the formation of cracks, pores, and other defects in the printed cemented carbides. Based on optimized WCCo composite powder, SLM technology, and subsequent heat treatment conditions, a nearly fully dense cemented carbide cutting insert with a bimodal grain microstructure was fabricated. The insert exhibited a Vickers hardness of (1 300 ± 20) HV30, a bending strength of (1 020 ± 130) MPa, and a compressive strength of (3 520 ± 240) MPa. The overall mechanical properties of this material are comparable to those of sintered cemented carbides with similar compositions and grain sizes, demonstrating promising application prospects.

GH4169D has been widely used in the manufacturing of aero engine blades, and the surface integrity after milling significantly affects the working performance of the blades. The milling experiment of GH4169D high-temperature alloy was carried out to study the influence of different process parameters on the surface integrity after milling. The results show that with the increase in milling speed, the surface roughness of GH4169D high-temperature alloy during milling along width cutting direction first increases and then decreases. The roughness along the width cutting direction increases with the increase in cutting width. Milling speed and cutting depth have a greater impact on microhardness. A large milling speed indicates a weak hardening phenomenon; a larger cutting depth indicates an obvious hardening phenomenon. The residual stress on the surface of GH4169D after milling is tensile stress, and a larger cutting speed indicates a larger residual tensile stress. The same relationship is shared between the residual tensile stress and the feed per tooth. When the milling speed becomes larger, the depth of the surface residual stress gradually becomes larger, and the peak of the residual compressive stress becomes smaller. As the milling width becomes larger, the depth of the maximum residual compressive stress does not change significantly, but the peak changes significantly. ap is within 0.16-0.24 mm, and the surface residual stress changes significantly. The depth of the maximum residual compressive stress increases, and the peak value decreases. The plastically deformed layer becomes thinner with increasing milling speed and thicker with increasing cutting depth.

Cemented carbides are indispensable in modern industry due to their various superior properties, but the contradiction between their hardness and toughness limits further performance improvement. Multi-scale material calculation methods integrate multi-scale theoretical models with key experiments, which ensure the efficient development of new materials and provide scientific support for the strengthening and toughening of cemented carbides. This article introduced theoretical methods such as first-principles calculations, thermodynamic and kinetic calculations, phase field simulations, and finite element simulations and demonstrated effective measures for the synergistic enhancement of strength and toughness in cemented carbides, including binder phase strengthening and toughening (nano-scale phase precipitation), hard phase strengthening and toughening (spinodal decomposition), and microstructure optimization (surface gradient structures and whisker toughening). It also discussed the efficient enhancement of cemented carbide performance through a combination of theoretical design and key experimental validation. Multi-scale material calculation methods can provide a theoretical basis and practical guidance for designing and preparing high-strength and high-toughness cemented carbide materials. In the future, it is necessary to further study the intrinsic mechanisms of material microstructure evolution and its structure-property relationships on this basis, so as to promote innovation and progress in the development of cemented carbide materials.

The deep sea contains abundant key metal mineral resources, and the effective development of deep-sea mineral resources is of great significance for alleviating land resource depletion, ensuring national mineral resource security, and promoting the development of key deep-sea technologies. Based on the overview of international deep-sea mineral resources and the current development status of deep-sea mining technology, this article investigated and analyzed the application requirements of cemented carbide materials in deep-sea mining equipment. By taking the picks of polymetallic sulfide mining vehicles as an example, the specific requirements of deep-sea mining for the performance of cemented carbide materials were discussed. Key technologies for cutting and crushing cemented carbide materials used in deep-sea metal mineral development were proposed, providing a reference for the application and development of cemented carbide materials in deep-sea mining.

Multi-principal-element alloys (MPEAs), including high entropy alloys (HEAs), consist of multiple main elements, altering the design concept of traditional alloys. They exhibit excellent strength-plasticity synergy, corrosion resistance, and high-temperature resistance, providing a flexible and efficient approach to optimizing material performance. In high-performance hard alloys, the concept of high entropy has been significantly applied in both the binder phase and the hard phase. This paper studied multi-principal-element binder and hard phases, focused on the influence of high entropy on the microstructures, strength and toughness control, and service performance of hard alloy materials, and introduced recent progress by the authors. Finally, the development prospects of high-entropy hard alloys were discussed.

Nanocarbon / copper (Cu) composites have been regarded as a strong competitive candidate for the next generation of high-performance Cu matrix materials with structural and functional integration. However, the strengthening efficiency of nanocarbon and Cu is low due to poor interfacial wettability and weak interfacial bonding. To improve the interfacial bonding between nanocarbon and Cu, researchers have proposed the use of the interface of tungsten carbide (WC)-modified composites, which possess strong wettability with both Cu and carbon and has gradually become a research hotspot in this material field. Therefore, this article reviewed the preparation, microstructure, and properties of Cu matrix composites reinforced with WC-modified nanocarbon in China and abroad. The interfacial reactions and crystallographic orientation relationship of the composites were analyzed. The roles of WC in strengthening and toughening, as well as the electrical and thermal conductivity of the composites, were discussed. In addition, it was suggested that future research on high-performance WC-modified nanocarbon/Cu composites should focus on the influence of the interfacial structure on the properties of the composites, the mechanism of action, and the design of heterogeneous structure configuration.

Chromium carbide is a high melting point material with good wear resistance, corrosion resistance, and oxidation resistance under high temperature environments. Chromium nitride is a ceramic material with high hardness, high melting point, and excellent chemical stability. They have excellent chemical stability and wear resistance and have been widely used as a coating of materials. To obtain high-quality chromium carbide and chromium nitride powders, stable physical properties and micro-topography control are required. In addition, the control of iron, silicon, calcium, and other trace impurities is necessary. A method for rapid determination of aluminum, silicon, calcium, and iron in chromium carbide and chromium nitride by inductively coupled plasma emission spectrometry was established. Microwave digestion of samples was conducted by using hydrofluoric acid and nitric acid. High-purity chromium matrixes were matched, and the standard working curve method was used to determine aluminum, silicon, calcium, and iron in chromium carbide and chromium nitride. The intensity of each element showed a good linear relationship with concentration, and the corresponding correlation coefficients were all greater than 0.999. The detection limits of the method were less than 0.0005%, and the lower limits of quantification of the method were less than 0.0015%. The tested relative standard deviation of each element ranged from 0.30% to 6.94%, and the spiked recoveries ranged from 96.0% to 105.0%. The method was simple and sensitive, and it could meet the production quality control requirements of cemented carbide or thermal spray powders.

In order to investigate the effect of alkaline cleaning agents on cobalt loss on the surface of WC-10%Co cemented carbide insert, APMT1135PDER-M1 and WC-TiC-TaC-6%Co cemented carbide insert, WNMG080412-DX, cleaning machine cleaning and cleaning agent soaking tests were conducted. The results indicate that alkaline cleaning agents are prone to causing cobalt loss on the surface of cemented carbide inserts; WC-TiC-TaC-Co cemented carbide insert, WNMG080412-DX, is more prone to cobalt loss than WC-Co cemented carbide insert, APMT1135PDER-M1 after three consecutive cleaning or soaking cycles (especially in alkaline cleaning agents such as sodium hydroxide + potassium hydroxide + amino trimethylphosphonic acid, as well as potassium hydroxide + amide + 2-butoxyethanol). The surface cobalt content is much lower than the set cobalt content of the substrate; the surface cobalt content of the inserts that have already been cleaned and lost cobalt after wet sandblasting approaches the set value of the substrate. It is suggested that the WC-TiC-TaC-Co cemented carbide insert should be cleaned at most once before coating in actual production. If backwashing is required due to surface cleanliness or other reasons, wet sandblasting treatment should be carried out first before cleaning.

In this paper, the precursor of the cobalt-ammonia complex was prepared by adding catalysts, organic polymerization dispersants, and initiators with cobalt sulfate heptahydrate as raw material and ammonia water as a complexing agent. It was then transferred into a high-pressure stirred reactor, heated, and stirred. After reaching the set temperature, hydrogen at a certain pressure was introduced for the reaction. The reaction product was centrifuged with deionized water and methanol, and the ultrafine cobalt powder was obtained after vacuum drying. The effects of reaction temperature, cobalt-ammonia complex ratio, and hydrogen pressure on the actual yield of ultrafine cobalt powder, as well as those of initiator, catalyst, and dispersant dosages on the Fisher particle size of ultrafine cobalt powder were studied. The results show that ultrafine spherical cobalt powder with Fisher particle size of less than 0.6 μm, uniform particle size distribution, and actual yield of greater than 99.5% can be synthesized by controlling the amount of initiator, catalyst, and dispersant when the reaction temperature is 140 °C; the hydrogen pressure is 2.5 MPa, and n (Co)∶n (NH3) is 1∶2.3.

Chemical vapor deposition (CVD) multilayer composite coating can effectively improve the life of the cutting tool, and the cutting temperature is one of the important factors affecting the coating performance. In this paper, the back face wear of tools with different coating structures for cutting 45 steel was compared by experiment, and the cutting temperature was obtained by finite element simulation. According to the finite element simulation and experimental results, the cutting temperature was considered to analyze the life of tools with different CVD multilayer composite coating (TiCAl2O3-TiN) for cutting 45 steel. The results show that when cutting 45 steel, the outermost tool without TiN coating has the shortest life. The coating structure has little effect on the maximum temperature of the tool tip, and the difference between tools with different coating structures is only less than 10 °C. The outermost tool coated with TiN coating can reduce the high-temperature area of the rake face. In order to improve tool life, when the cutting temperature is below 850 ° C, the innermost TiC coating thickness should be reduced appropriately, and the outermost TiN coating thickness should be increased. After the cutting temperature exceeds 850 °C, TiN coating thickness should be appropriately reduced, and Al2O3 coating thickness should be increased.

To investigate the effect of W doping on the microstructure and properties of CrAlN coatings, coatings of Cr0.36Al0.64N, Cr0.34Al0.64W0.02N, and Cr0.32Al0.63W0.05N were prepared by using the cathodic arc evaporation method. The composition, microstructure, thermal stability, mechanical properties, and oxidation resistance of the coatings were studied by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), simultaneous thermal analyzer, and nanoindenter. All three coatings exhibited a face-centered cubic structure. The hardness increases with the W content, rising from (28.61±0.82) GPa of Cr0.36Al0.64N to (30.87±0.80) GPa of Cr0.34Al0.64W0.02N and (32.37 ± 1.44) GPa of Cr0.32Al0.63W0.05N. W doping reduced the“droplet”defects generated during the cathodic arc evaporation process, with defects decreasing as W content increases. The addition of W suppressed the thermal decomposition of CrAlN coating and enhanced its thermal stability. However, W doping reduced the oxidation resistance of the CrAlN coating. After 15 hours of isothermal oxidation at 1 100 ° C, The oxide layer thicknesses of the Cr0.36Al0.64N, Cr0.34Al0.64W0.02N, and Cr0.32Al0.63W0.05N coatings were approximately 260.6 nm, 359.8 nm, and 445.9 nm, respectively.

The cutting force of the indexable insert drill affects the radial force balance and chip shape of the tool, lowering the dimensional accuracy and surface quality of the workpiece. It is particularly important to study the insert cutting force for stable applications of the indexable insert drill. In this paper, the insert groove of the indexable insert drill was optimized based on cutting force analysis. Firstly, the insert groove parameters were selected, and the orthogonal test scheme was designed. The key parameters affecting the insert cutting force were determined through simulation results. Secondly, the parameters were ranked based on their influence, and the optimal groove parameter combination was obtained. Finally, it was verified by a drilling test. The radial cutting force of the insert of the indexable insert drill was reduced by 18.1% by optimizing the insert groove parameters. The difference between finite element simulation and drilling experiment was only 6.61%. The results show that the orthogonal test method based on finite element simulation is suitable for the insert groove optimization of the insert groove and can effectively reduce the cutting force.

Nuclear fusion energy is considered to be one of the ideal energy sources in the future due to its high energy density, cleanness, and safety. In order to improve the performance of tungsten as the first wall and divertor material of nuclear fusion reactor, tungsten alloy (KW) strengthened by potassium (K) bubble diffusion via K doping is one of the methods to improve the high temperature stability of tungsten. In this paper, the microstructure and recrystallization behavior of K-doped tungsten with different K contents were studied. High-density KW was prepared by powder metallurgy, and sintering and rolling were carried out. The results show that the addition of K significantly increases the recrystallization temperature of tungsten, among which the alloy with higher K content (81 μg / g) shows the highest recrystallization temperature (1 500 ℃ ). Scanning electron microscope (SEM) analysis shows that K bubbles are mainly distributed at the grain boundaries, effectively pinning the grain boundaries, hindering the migration of grain boundaries, and improving the high temperature thermal stability of the material, which provides an optimization reference direction for the application of tungsten-based alloys in nuclear fusion reactors.

The study investigated the effect of Cr3C2 and VC doping on the magnetic properties of WC-6%Co cemented carbide with varying carbon contents. Meanwhile, by employing ultrafine-grained tungsten carbide with a particle size of 0.4 μm and submicron tungsten carbide with a particle size of 0.7 μm, the trend of changes in the coercive force and relative magnetic saturation of the cemented carbide under different particle sizes was observed, along with the characteristics of the corresponding microelement distribution. The results show that in the WC-6%Co cemented carbide system, when it is in the two-phase region, the relative magnetic saturation strength of the cemented carbide under different grain sizes increases with the increase in carbon content, showing a positive correlation. When only Cr3C2 is added, a portion of Cr may precipitate in the form of Cr-rich composite carbides (M7C3), dispersing and inhibiting grain growth. Meanwhile, an increase in carbon content enhances the precipitation of M7C3, further intensifying its grain refinement effect. Consequently, a positive correlation is observed between the coercive force and carbon content. When the mass fraction of Cr3C2 is 1%, and that of VC is 0.3%, the interfacial segregation of VC plays a dominant role in inhibiting grain growth, thereby weakening the influence of M7C3. Simultaneously, an elevated carbon content leads to a reduction in the liquidus, facilitating grain growth. Due to the competing effects of various mechanisms, the introduction of composite inhibitors consisting of Cr3C2 and VC results in a negative correlation between the coercive force of fine-grained cemented carbide and carbon content.

In this paper, WC-32%(Co-Ni)-1.3%Cr cemented carbide was studied, and three cemented carbide samples with different cobalt / nickel ratios were prepared by powder metallurgy. Through performance testing, microstructure analysis, and electrochemical polarization curve testing, the influence of cobalt and nickel content changes on the microstructure, mechanical properties, and corrosion resistance of WC-32%(Co-Ni)- 1.3%Cr cemented carbide with high bonding agent was studied. The results show that with the decrease in cobalt content and the increase in nickel content, the cobalt magnetism, coercivity, and hardness of the cemented carbide decrease linearly. The grain size and density of the cemented carbide remain almost unchanged, and the transverse rupture strength of the cemented carbide changes very little at around 2 400 MPa. The corrosion trend of WC-32%(Co-Ni)-1.3%Cr cemented carbide with a high bonding agent varies with the change in cobalt / nickel ratio in neutral and acidic solutions. As the cobalt content decreases, and the nickel content increases, the self-corrosion potential of the cemented carbide increases, and the corrosion current density decreases in H2SO4 solution with pH = 1. The corrosion resistance of the cemented carbide with a cobalt/nickel ratio of 1:3 is much higher than that of the cemented carbide with a cobalt/nickel ratio of 1:1 or 3:1. High-nickel cemented carbide can significantly improve the corrosion resistance of the cemented carbide in acidic solutions. With the decrease in cobalt content and the increase in nickel content, the self-corrosion potential of the cemented carbide in NaCl solution with pH = 7 increases, and the corrosion current density decreases. There is no significant difference in corrosion resistance between cemented carbides with a cobalt/nickel ratio of 1:1 and 1:3, but it is much higher than the corrosion resistance of cemented carbides with a cobalt/nickel ratio of 3:1.

This article selected 06 type WC powder as the research object and processed it by using jet milling technology. The influence of the jet milling technology on the microstructure morphology, particle size, particle size distribution, and related characteristics of the powder was studied. The differences in the properties of WC powder processed with the jet milling technology and the ball milling technology were compared. The research results indicate that the rotational speed of the grading wheel has a significant impact on the particle size and uniformity of the WC powder produced during the jet milling process. The higher rotational speed of the grading wheel indicates a smaller particle size and more concentrated particle size distribution of WC powders. When the rotational speed of the grading wheel is ≥ 3 900 r/ min, particles with a size of ≥2 μm are completely eliminated. However, the excessively high rotational speed of the grading wheel will reduce equipment production efficiency. When the rotational speed of the grading wheel reaches 4 200 r/min, the equipment production efficiency drops to 53.8 kg / h, while the oxygen and impurity content of the powder is increased. Compared with that produced by ball milling, the WC powder produced by jet milling has a more concentrated particle size distribution and fewer impurity content, and the microstructure of the alloy produced is more uniform. The powder obtained by jet milling is conducive to the preparation of high-quality ultrafine grain cemented carbide products.

In this paper, the problems of uneven arc radius and size in polishing and passivating the cutting edge of the cemented carbide blade by commonly used roller brush passivation equipment were analyzed. Based on the working principle of roller brush passivation equipment, this paper analyzed the reasons for the inconsistent arc radius and size in passivating the cutting edge of cemented carbide blades from two aspects of brush motion and brush wear. Through the mathematical modeling of the equipment movement mode, it is found that when the product enters the brush and leaves the brush, the number of product rotations is not an integer, which will result in a longer processing time for a certain corner or a certain cutting edge of the product. At the same time, the uncertainty of brush wear will cause a difference in the actual processing time, which causes the inconsistency of the arc radius and size of the cutting edge. This is the inevitable defect of the equipment design.

In the production of cemented carbides, hafnium is often used as an additive to improve the mechanical properties of cemented carbides. Therefore, accurate determination of the hafnium content in cemented carbides is of great significance. The existing chemical volumetric method for determining hafnium in cemented carbides has the disadvantages of high risk, complex operation, and low analysis efficiency. This article explored the determination method of hafnium in cemented carbides from the aspects of sample pre-treatment, selection of analytical lines, and exploration of matrix effects. It established a method for determining the hafnium content in WC-Co cemented carbides by using inductively coupled plasma atomic emission spectrometry, which was safe, efficient, and simple to operate, at a low cost. Under the selected conditions, a mixed solution with sulfuric acid: ammonium sulfate (1: 1) was combined with citric acid and hydrogen peroxide to serve as the pretreatment solvent, and the hafnium spectral line 264.141 nm was selected as the analytical spectral line. The standard solution was prepared using the matrix matching method. The linearity of the method calibration curve was greater than 0.999 9, and the linear range was 0.0-2.0 μg/mL. The detection limit was 0.008 4 μg/g, and the recovery rate was 99.17%-103.63%. The RSD was less than 0.758%. This method provided a reliable method for detecting the hafnium content in WC-Co cemented carbides.

This paper studied the influence and mechanism of different iron-based catalysts on IIa type cultivated diamonds under high temperatures and pressures. The results show that the optimal crystallinity of the FeAl-C catalyst is 72.2%, and the weekly yield is 25.61 ct (1 ct = 0.2 g). The average weight of a single diamond is 1.19 ct. FeCo-C catalyst has a weekly yield of 44.37 ct, and the average weight of a single diamond is 2.11 ct, but the optimal crystallinity is 36.8%, and there are many defects. Scanning electron microscope (SEM), energy disperse spectroscopy (EDS), and electron back scattering diffraction (EBSD) are used to reveal the effects of FeAl and FeCo catalysts on the growth of cultivated diamonds due to structural differences. The results show that the average mass fraction of Al and Fe in the FeAl catalyst is 4.86% and 95.14%, respectively. The average mass fraction of Co and Fe in the FeCo catalyst is 37.33% and 62.67%, respectively. The difference in solid solubility between metals leads to the difference in phase distribution and grain orientation. The grains of the FeAl catalyst are coarse, large, and uniform, with the same orientation, and the formed single-phase structure and single texture reduce the catalytic activity when the catalyst selectivity is enhanced, resulting in uniform transfer and precipitation of carbon on the crystal seed surface, which promotes the formation of high-quality crystals and leads to a low yield of the FeAl system. The grains of the FeCo catalyst are small but heterogeneous, containing multiple solid solution phases and multiple textures, which increase the catalytic activity of the catalyst and speed up crystal growth and yield. As the selectivity decreases, the process of carbon transfer and precipitation on the crystal seed surface is more complicated, and the morphology is unstable, which makes it easy to produce more crystal defects.

Coarse-grained cemented carbide demonstrates exceptional thermal conductivity and resistance to thermal fatigue, rendering it highly promising for applications in mining tools and hard surface materials. As the main intermediate product of tungsten, ammonium paratungstate (APT) with high-alkaline metal content facilitates the production of coarse particles of tungsten carbide powder for the preparation of coarse-grained cemented carbide. This investigation employed an ammonium tungstate solution as a raw material to explore the initial sodium content in the solution, as well as the types and quantities of additives, crystallization rate, and the influence of APT washing times on sodium content in APT crystals. The results indicate that the type of additives has no effect on the sodium content in APT crystals, but the amount of sodium hydroxide, crystallization rate, and APT washing times have a greater impact. By controlling the adding amount of sodium hydroxide at a sodium-tungsten mass ratio of 4‰ and achieving a crystallization rate of 90%, high-sodium APT products with a sodium content exceeding 0.029% can be produced after four rinses with pure water. Furthermore, other impurity elements meet zero-grade requirements of national standards.

The WC-13%Co cemented carbide was treated by liquid phase rapid cooling (1350 °C and above) and solid phase quenching rapid cooling technology (1100 °C and below) at high temperatures. The effects of two treatment methods on the microstructure and physical & mechanical properties of the cemented carbide were studied. The results show that compared with the sintered state, the microstructure of the cemented carbide after rapid cooling treatment has no obvious change, while the grain size after liquid phase rapid cooling treatment and solid phase rapid cooling treatment increases by 28.13% and 18.75%, respectively. In terms of physical & mechanical properties, the rapid cooling treatment has a certain change compared with the sintered state. Compared with the solid phase rapid cooling treatment, the physical & mechanical properties of the liquid phase rapid cooling treatment change significantly. Compared with the sintered state, the cobalt magnetic and coercive magnetic forces decrease by 4.5% and 1.0 kA/m, respectively. The vickers hardness, crack length and solid solubility of W in the cobalt phase increase by 0.98 GPa, 33.3 μm and 6%, respectively. The main reason for the significant change is that the solid solubility of W in the binder phase Co increases significantly after the liquid phase rapid cooling treatment, which has a significant strengthening effect on the cemented carbide.

A single factor method was used to conduct milling experiments on 7075 aluminum alloy, and the effects of rotational speed and feed rate on chip morphology, surface roughness, machined surface morphology, and residual stress were analyzed. The results show that as the rotational speed and feed rate increase, the degree of chip curling increases, resulting in regular curling and breaking of chips. When the feed rate f=0.05 mm/r, the chips exhibit two states, and irregular chips can easily cause instability in the cutting process, leading to poor surface quality. Higher rotational speed indicates smaller surface roughness. As the feed rate increases, the surface roughness first decreases and then increases, the reason for the initial decrease is that when the feed rate f=0.05 mm/r, the cutting process is unstable, resulting in a larger surface roughness value than when f=0.1 mm/r. High rotational speed is beneficial for forming more regular machined surface patterns, with fewer adhesives and clearer and more regular surface contours. A larger feed rate ensures a wider and deeper blade pattern and rougher surface contour. Under the squeezing effect, the residual stress on the surface of the aluminum alloy during cutting presents a compressive stress state, and as the rotational speed gets higher, the residual compressive stress on the machined surface becomes smaller. As the feed rate increases, the cutting force and the residual compressive stress are larger.

99% alumina ceramics doped with Cr₂O₃-Y₂O₃-MgO were prepared by pressureless sintering at temperatures of 1 480 °C, 1 500 °C, 1 530 °C, and 1 550 °C. The effects of varying doping amounts of Cr₂O₃ on the densification, microstructure, microwave dielectric properties, and insulation properties of the 99% alumina ceramics were studied. The results show that appropriate amounts of Cr₂O₃, Y₂O₃, and MgO can promote sintering, reduce intergranular voids, improve density, and enhance overall performance. Under the conditions of w(Cr₂O₃) = 0.4%, w(Y₂O₃) = 0.24%, w(MgO) = 0.16%, and sintering temperature of 1 530 °C, the ceramics exhibit a density of 3.919 cm³, a dielectric constant (ε_r) of 9.985, a dielectric loss (tanδ) of 0.000 5, and a breakdown voltage of 25.3 kV. The doping of Cr₂O₃ improves the microwave dielectric and insulation properties of the 99% alumina ceramics, showing promising potential in electronic packaging materials.