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Quick Search     Adv Search   2024 Vol. 34, No. 01 Published: 2024-02-10   1 Progress on manufacture of powder metallurgy HSS/tool steels and development on their applications Hot! YU Yang，XU Shenghang，LIAO Jun DOI: 10.13228/j.boyuan.issn1006-6543.20230174 HSS and tool steels perform specially with their high mechanical and thermal properties such as high strength and toughness, high hardness, high wear resistance, and good heat resistance, which are widely used in in‐ dustries such as metalworking, plastic injection molding, and automotive manufacturing, etc. Conventionally, they are prepared by traditional casting and forging process, which always introduce compositional segregation and coarse carbides in their microstructure. These micro defects are difficult to eliminate through conventional process‐ ing methods such as forging, leading to the deterioration in material properties. The powder metallurgy process pro‐ vides an uniform microstructure, fine dispersive carbides, and high alloy composition, which allows for the manu‐ facturing of complex shapes and structures of the final products. Through this approach, the tool and die products have the advantages of higher performance, higher precision, and longer life, and have important applications pros‐ pects in the high-end manufacturing industry. In this work, a comprehensive review of the production technologies and applications of powder metallurgy HSS and tool steels are provided. Besides, the technological innovations in the industrial production, the manufacture methods, and the microstructural properties of powder metallurgy HSS and tool steels are discussed in details. Furthermore, the classifications and applications of these materials, offering an outlook on the future development trends in powder metallurgy HSS and tool steels are summarized. 2024 Vol. 34 (01): 1-10 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 11 Study on the microstructure and sintering properties of Cu-Sn powder prepared by the premixing method and prealloying method Hot! CHEN Pengfei，MO Wenjian，YI Cui，WANG Andong DOI: 10.13228/j.boyuan.issn1006-6543.20230013 Cu-Sn powders were prepared by pre-mix and pre-alloy process, the microstructure and phase changes of Cu-Sn alloy were studied after sintering, and the sintering properties of Cu-Sn powders prepared by these two methods were tested and compared. The experimental results show that the microstructure of pre-mixing CuSn10 and CuSn20 is composed of α phase and α + δ eutectic tissue after sintering, while that of pre-alloy CuSn10 is α phase. After sintering, the pre-mixed Cu-Sn green compacts expand, on the contrary the pre-alloyed green com‐ pacts shrinkage. In addition, the strength, oil content and effective oil content of the pre-alloyed Cu-Sn parts are higher than those prepared by the pre-mixing method. 2024 Vol. 34 (01): 11-16 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 17 Research on deformation law of non-solid supported thin-walled surface by selective laser melting Hot! DUAN Xianyin，HU Zujiang，DENG Ben，LIN Zhixiong，LONG Tao DOI: 10.13228/j.boyuan.issn1006-6543.20230015 The selective laser melting forming technology is increasingly used in the manufacture of complex com‐ ponents for aerospace equipment. However, such parts have thin-walled curved features have a large residual stress, which could induce large residual stress and deformation and seriously restrict the forming accuracy and quality. AlSi10Mg is widely used in the production of parts in the field of additive manufacturing due to its low density, high specific strength and good corrosion resistance. In this paper, we analyze the influence of the process parameters and geometric features on the support connection by simulating the laser-selective melting of thinwalled surface features under non-solid support, and study the residual stress distribution and deformation law of the surface features under non-solid support based on this simulation. The thermoplastic method is used to simulate the connection of the non-solid support with different support forming laser power and support structure, and the support parameters are selected with the goal of connection effect. The residual stress and deformation distribution of thin-walled surface features with different wall thicknesses and forming heights are simulated, experimentally verified and discussed based on the intrinsic strain model with the application of the selected support parameters. The simulation results show that the strength of the non-solid support connection is related to the laser power. The decrease of the laser power leads to the decrease of the stress level at the support connection. The stress values at the support connection of each group decrease by14.7%,14.6% and 17.3% respectively with the decrease of the la‐ ser power. When optimizing non-solid support parameters for forming simulation and experiment of thin-walled curved parts, it is found that the peak deformation of thin-walled curved parts increase with the rise of forming height, and the thinner the wall thickness of the parts, the greater the peak deformation. Under the condition of using laser power of 350 W, 3×3 grids and adding independent external contour support, the non-solid support con‐ nection effect of AlSi10Mg is the best, and with the increase of laser power, the support connection is also stronger. The addition of non-entity contour support can effectively improve the support connection. The local deformation of thin-walled curved parts with non-solid support is obviously improved. The residual stress distribution of thinwalled curved parts is mainly affected by the Z-direction normal stress of the parts, and increases with the increase of the thickness of the parts. 2024 Vol. 34 (01): 17-29 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 30 Numerical simulation and experimental study on the influence of the length of guide tube and atomization pressure on gas reflux Hot! TAN Xiaolian，GUO Zhen，LI Chuanfeng，LI Chuanzhen，ZHANG Hongzhi，SU Xiaofeng DOI: 10.13228/j.boyuan.issn1006-6543.20230003 Spherical powder for metal 3D printing is generally prepared by the technology of atomization, the met‐ al powder prepared by electrode induction-melting gas atomization (EIGA) without crucible has the advantages of low oxygen increment, high fine powder yield, high sphericity and good fluidity. In this paper, a numerical simula‐ tion of the airflow field at the bottom end of the guide tube of the atomizing nozzle is carried out, and the influence of the length of the guide tube and the atomization pressure on the gas reflux is studied, and the simulation results are verified by the atomization experiment. The results show that there is a critical value for the length of the guide tube. When the length is lower than the critical value, the flow velocity of the gas outside the annular seam of the atomizing nozzle is higher than that inside, and the gas is easy to return to the inside of the guide tube, resulting in more defective powders. When the length is higher than the critical value, the flow velocity of the gas inside the annular seam is higher than that outside, the gas reflux disappears, and the number of defective powders is greatly reduced. The atomization pressure mainly affects the particle size of the powder. The greater the atomization pres‐ sure, the smaller the powder particle size. 2024 Vol. 34 (01): 30-36 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 37 Thermodynamic analysis and reaction kinetic for the preparation of aerospace-grade AlV85 master alloy Hot! YUAN Zikai，HUANG Zhaokuo，YU Jiyang，TENG Aijun，CHANG Zhi DOI: 10.13228/j.boyuan.issn1006-6543.20220191 The Gibbs free energy, adiabatic temperature and calorific value of AlV85 master alloy prepared by alu‐ minothermal method were calculated according to the thermodynamie prineiples, the process was studied using dif‐ ferential thermal analysis, the kinetic equations of AlV85 alloy produced by the aluminothermal method with differ‐ ent sizes of Al powder were constructed. The reaction of AlV85 master alloy by the aluminothermal method can be carried out and maintained spontaneously，with adiabatic temperature of 2 327 K and calorific value of 4 169 J/mol. Al powder is melted first and reacts with solid V2O5 to replace V and produce part of AlmVn, then part of V and AlmVn react to form V solid solution at about 1 000 K. The particle size of aluminum powder has a great influence on the reaction process and reaction products; The kinetic equations of AlV85 master alloy preparation with differ‐ ent particle sizes aluminum powder is constructed, the smaller the particle size, the lower the activation energy and the higher the frequency factor. 2024 Vol. 34 (01): 37-43 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 44 Study on the morphology and application properties of small particle size nickel-manganese binary precursor Ni0.6Mn0.4(OH)2 Hot! YANG Yongsheng，LIU Fei，SUN Lei，LIU Jiying，MI Xixue，WANG Yaoxi DOI: 10.13228/j.boyuan.issn1006-6543.20230001 The development of low cobalt or cobalt-free ternary precursor materials is of great significance for the development of low cost and high energy density ternary lithium electric materials. In recent years, due to the longterm high price of cobalt salt, it has become a constraint on the development of new energy vehicles. Among them, medium/high nickel or lithium rich manganese based cathode materials have attracted widespread attention. The electrochemical performance of cathode materials based on lithium batteries largely depends on the performance of precursors. It is particularly important to study the effects of ammonia concentration, pH value, nucleation method, and reaction temperature on surface morphology by preparing low cobalt or cobalt free precursors. The precursor material Ni 0.6Mn0.4(OH)2 was prepared by coprecipitation controlled crystallization method with nickel sulfate and manganese sulfate as raw materials. During the preparation process, the effects of ammonia concentration, pH val‐ ue, nucleation method, and reaction temperature on the morphology of the product were mainly investigated. The effects of ammonia concentration, pH value, nucleation mode and reaction temperature on the surface morphology of the precursor were characterized by SEM and EDS. The effects of different ammonia concentrations on the phys‐ ical and chemical indicators of the material were characterized by carbon sulfur analyzer, tap density tester, and BET. The effect of different ammonia concentrations on the electrochemical performance of positive electrode ma‐ terials was characterized through electrochemical testing. The results show that when the ammonia concentration increases from 0 mol/L to 0.14 mol/L, the primary particles of the precursor grow gradually from filamentation to transverse broadening, and the increase of ammonia concentration is conducive to the preparation of low-sulfur and dispersive precursor. The influence of pH value on the surface morphology of precursors is mainly manifested in the nucleation rate and growth rate of precursors, as well as the degree of primary particle thickness. High pH val‐ ues prioritize nucleation with growth as a secondary factor, while low pH values have the opposite effect. Com‐ pared to the above two influencing factors, the nucleation method mainly affects the sphericity of the precursor and the core structure of the precursor. The nucleation method using nickel cobalt manganese solution, ammonia solu‐ tion, and sodium hydroxide solution simultaneously has poor sphericity, but high capacity and poor circulation. However, the nucleation method using nickel sodium solution simultaneously has high sphericity of the precursor, and good capacity and circulation of the positive electrode material. The reaction temperature mainly affects the thickness and sphericity of the precursor primary particles. The higher the temperature, the thicker the primary par‐ ticles, and the worse the sphericity. Finally, the ammonia concentration is determined to be 0.14 mol/L, with pH ranging from 11.5 to 11.6. The nucleation method uses nickel solution and sodium hydroxide solution simultane‐ ously to prepare precursor Ni0.6Mn0.4(OH)2 with good morphology and excellent electrochemical performance as the cathode material. The results show that the precursor products with excellent performance can be prepared only when the appropriate ammonia concentration matches the appropriate reaction pH value, nucleation method and re‐ action temperature. 2024 Vol. 34 (01): 44-50 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 51 Effect of graphite lubrication component type on the microstructure formation and properties of high-speed braking Cu-based friction materials Hot! FAN Jianglei，WANG Jiaojiao，WANG Xiao，WEI Zexin，HAO Yuanfeng，LIU Jianxiu DOI: 10.13228/j.boyuan.issn1006-6543.20220233 Cu-based friction materials with different lubrication component such as the flake graphite, spherical graphite, coke, artificial graphite, and cryptocrystalline graphite, were prepared by powder metallurgy technology. The tribological and brake performance of Cu-based friction materials with different lubrication component were tested by the MM3000 friction and wear tester. The results show that the average friction coefficient of the Cubased friction material with artificial graphite as lubrication component is the highest (> 0.40), but the wear loss is the largest of all at the speed of 3 000~7 000 r/min. The friction coefficient of the Cu-based friction material with coke is the second (> 0.375), and the wear loss is the smallest of all. The friction coefficient and wear loss of the Cu-based friction material with coke is good than the Cu-based friction material with commonly used flake graph‐ ite. Under the braking condition of 7 000 r/min, the instantaneous friction coefficient of Cu-based friction material with artificial graphite is the highest, and the braking time is short. However, the surface temperature rise of the Cu-based friction material with artificial graphite is the largest. The instantaneous friction coefficient and braking time of the Cu-based friction material with coke is second, but the surface temperature rise of friction material is the smallest. The overall performance of the Cu-based friction material with coke is better than the friction material with flake graphite. Therefore, Cu-based friction materials with coke as lubrication component have better tribolog‐ ical and braking properties, relatively. 2024 Vol. 34 (01): 51-59 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 60 Microstructure evolution and fracture mechanism of diffusion bonded MHC/GH4099 joint by hot isostatic pressing Hot! HUANG Zanjun，ZHANG Longge，CHE Hongyan，WANG Tiejun，DONG Hao，CAO Rui DOI: 10.13228/j.boyuan.issn1006-6543.20220164 To form a satisfactory bonding between Molybdenum-Hafnium-Carbon (MHC) and GH4099 alloy，in‐ terlayers are used to alleviate the huge property difference, such as thermal expansion coefficient of the two materi‐ als. This study focused on interlayers and different layer composition to investigate the bonding microstructure and fracture mechanism.Direct diffusion bonding between MHC and GH4099 is difficult due to the low diffusion rate and brittle intermetallic compound formed. Hot isostatic pressing diffusion bonding technology (HIP-DB) was ad‐ opted as the major process in this study by inserting layers between them. The effect of different interlayers (NiCr-Si-B, Ag-Cu-Ti, Ti-Cr-Ni, Nb-Ni ) on the mechanical performance of welded joint between MHC and GH4099 alloys by (HIP-DB) was investigated. Optical Microscope (OM) and Field Emission Scanning Electronic Micro‐ scope (FE-SEM) with energy dispersive spectroscopy (EDS) analysis were applied to analysis the microstructures of the bond, fracture morphology and element distribution. Ni-Cr-B-Si interlayer tends to form brittle Mo-Ni inter‐ metallic phase that is regarded as the main cause of brittle fracture morphology observed. Bond strength with NiCr-B-Si interlayer is very poor. Ag-Cu-Ti interlayer can both react with MHC side and GH4099 side, which lend bond shear strength of 27 MPa. Microstructure observation shows that there are Kirkendall pores reside in the frac‐ ture surface which is responsible for the low bond strength. Ti-Cr-Ni interlayer does not form an effective metallurgical bonding, which is attributed to the intrinsic weak strength of TiCrNi material and low HIP-DB process tem‐ perature. Nb-Ti interlayer forms good metallurgical bonding between MHC and GH4099. Effective diffusion has taken place in MHC/NbTi bond although some pores exist in this area, due to the significant difference of diffusion rate of Mo and Nb. The diffusion-induced reaction layers are determined to be the Mo-Nb solid solution, Ni8Nb, Ni 3Nb and Ni6Nb7. Their strength and thickness are measured in order to establish a correlation between the interfa‐ cial microstructure and joint properties. It is found that the precipitated phase Ni3Nb shows high strength and good plasticity, which is beneficial to the high-temperature performance of the joint. Cracks are initiated from the MoNb solid solution, and then intergranular fracture propagates across the central diffusion layer. Reliable MHC/ GH4099 bonding joints are obtained with Nb-Ni interlayer at 1 150 ℃/130 MPa/180 min in HIP process. The joint tensile strength/shear strength with Nb+Ni interlayer reach 84 MPa/41 MPa, which is higher than that with Ni-CrSi-B, Ag-Cu-Ti or Ti-Cr-Ni interlayer. 2024 Vol. 34 (01): 60-69 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 70 Study of extrusion volume on surface densification of powder metallurgical parts Hot! HUANG Xian，LUO Cheng，WANG Tianguo，HUA Jianjie，ZHANG Xiaodong，ZHANG Minghui DOI: 10.13228/j.boyuan.issn1006-6543.20220176 The effect of deformation on the depth of the surface densification layer of powder metallurgical Fe-CuMn-Mo-C materials was investigated using plastic densification techniques. By increasing the amount of deforma‐ tion, the pores on the surface of the parts were reduced and the surface densification depth and hardness were im‐ proved. The experimental results show that the surface of the powder metallurgy parts prepared by extrusion densi‐ fication technique can form a uniform densification layer and the surface hardness of the parts can be improved. When the finished deformation is increased to 0.4 mm and 0.6 mm, a dense layer of about 0.25-0.4 mm is formed on the surface of the powder metallurgical parts with a specimen density of 6.8 and 7.0 g/cm3. The depth and hard‐ ness of the surface dense layer increase with the amount of deformation, indicating that the amount of deformation is one of the most important factors influencing the surface densification effect of the parts. 2024 Vol. 34 (01): 70-75 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 76 Effect of heat treatment on microstructure and properties of TA15 titanium alloy formed by SLM Hot! YUAN Chenfeng，BAI Bing，CHENG Zonghui，CAI Xiaoye，FAN Zhao，HU Jiaqi DOI: 10.13228/j.boyuan.issn1006-6543.20220143 TA15 titanium alloy samples were prepared by selective laser melting (SLM) forming technology. The effects of heat treatment on microstructure, tensile and impact properties of TA15 titanium alloy samples were stud‐ ied. The results show that under the single heat treatment mode, with the prolongation of holding time and the in‐ crease of annealing temperature, α' martensite in the microstructure gradually decomposes, and the volume fraction of the secondary α phase and β phase gradually increases, and the tensile strength of the samples show a downward trend, but the fracture toughness increases at first and decreases subsequently. Under the heat treatment system of 850 ℃ for 4 h, the sample has better comprehensive properties, its tensile strength is 1 033 MPa, and the impact en‐ ergy is 38 J. Under the double heat treatment mode, the microstructure is mainly a basket-weave structure α+β twophase structure, the degree of microstructure homogenization is higher, which shows that the dispersion of macro‐ scopic properties is smaller, with an average tensile strength of 1 029 MPa and impact energy of 40 J. 2024 Vol. 34 (01): 76-83 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 84 Study on gelcasting process of alloy powder made of grinding mud Hot! CHE Xiaozhou DOI: 10.13228/j.boyuan.issn1006-6543.20220179 The steel powder was separated from grinding mud produced in Knife and scissors industry. A new al‐ loy powder was prepared by adding appropriate amount of elements to the purified grinding mud steel powder. Gel‐ casting process using the hydroxyethyl methacrylate as organic monomer and the tetraethylene glycol dipropylen‐ ate as crosslinker was investigate respectively. Sintered body with good surface condition was obtained after de‐ moulding, drying and sintering the green body at 1 400 ℃ for 2 h. The microstructure of the sintered body is com‐ posed of pearlite, carbide and micropore. The as-sintered specimen was then quenched at 1 050 ℃ and tempered at 180 ℃, respectively. Hardness of the sample after heatreatment is 50HRC. After 3 h salt spray test with 5% sodi‐ um chloride aqueous solution, the corrosion degree of the as-heattreated sintered body is much lower than that of sintered bodys without heat treatment.It shows that sintered alloys made of grinding mud alloy have good corrosion resistance after quenching and low temperature tempering. 2024 Vol. 34 (01): 84-88 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 89 Research on tape-casting technology of metal thin film Hot! CAO Boyuan，FANG Yufei，WANG Yan，PU Bowei，REN Shangyuan，LI Rong DOI: 10.13228/j.boyuan.issn1006-6543.20220165 The tape casting method is applied to the production of metal films. Due to the large specific gravity of the metal powder and the complicated preparation process of the casting process, the metal film is easily deformed and cracked. In this paper, the influence of the content of various additives in the metal casting slurry on the form‐ ing process and sintering properties of the metal film was studied. The result shows that the binder content and vis‐ cosity have a decisive influence on the performance of the metal film. Adding 10% pore-forming agent can effec‐ tively control the phenomenon of particle agglomeration, membrane pore size distribution is concentrated, the gas transmission rate increases. The influence of solid content on the uniformity of the slab is verified. The solid con‐ tent is too low can cause surface cracking, uneven thickness, many defects and poor strength after sintering. And the solid content is too high, will lead to the film layer gas permeability decline, at the same time, the flexibility of the film layer will also be reduced. Pore forming material can significantly improve the surface agglomeration phe‐ nomenon of membrane layer and improve the binding force between particles. 2024 Vol. 34 (01): 89-93 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 94 High temperature oxidation performance and thermal shock resistance of TiN/Cr-coated zirconium alloy cladding Hot! XIAO Weiwei，LIU Yilong，HUANG Jinghao，LI Jiatao，LIU Shihong，YANG Chen DOI: 10.13228/j.boyuan.issn1006-6543.20220154 In order to study the high temperature oxidation properties and thermal shock resistance of TiN/Cr-coat‐ ed zirconium alloys, TiN/Cr-coated zirconium alloy samples were prepared by magnetron sputtering. High tempera‐ ture oxidation and thermal shock resistance experiments were carried out respectively, and the microstructure, phase and adhesion strength of the samples after high temperature oxidation and thermal shock resistance were characterized. The results show that there is a clear boundary between the TiN/Cr double-layer coatings prepared by magnetron sputtering, and there are round-like agglomeration protrusions on the surface of the samples, but the coating structure is dense and free of defects such as cracks and pores. After high-temperature oxidation, the sur‐ face Cr coating is partially oxidized to Cr2O3, which is an irregular polyhedral structure. Ti atoms from the TiN coating diffuse to the surface and combine with O to form TiO2, which is a long-striped structure. The Cr2O3 aggrega‐ tion area is bubbling. At the interface between the coating and the substrate, the in-diffused Cr atoms and the outdiffused Zr atoms form a Cr-Zr diffusion layer with a thickness of about 5 μm. At the same time, O atoms continue to diffuse into the sample and combine with Zr atoms to form ZrO2. Although the oxidation weight gain of the TiN/Cr coated zirconium alloy is smaller than that of the uncoated zirconium alloy, and the sample remains relative‐ ly intact, the internal zirconium alloy is oxidized due to the continuous diffusion of O atoms, indicating that the TiN/Cr coating cannot provide good long-term high temperature oxidation resistance for zirconium alloy. After the thermal shock test, the surface coating still completely covers the entire sample, but there is a molten pool-like area on the surface of the sample, accompanied by microcracks and pores, and the adhesion strength of the coating film/ substrate is significantly reduced. 2024 Vol. 34 (01): 94-101 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 102 The effect of pre-placed thickness of powder on the forming quality and properties of Mo2FeB2 coating Hot! YANG Jianghuai，LIAN Guofu，ZHANG hao，CAO qiang，QUE linzhi DOI: 10.13228/j.boyuan.issn1006-6543.20220189 In order to explore the influence mechanism of powder thickness on the forming quality and perfor‐ mance of Mo 2FeB2 coating, the Mo2FeB2 coatings were prepared by the laser cladding preset powder method. The influence of powder coating thickness on the morpgology, microstructure, microhardness, and wear resistance of Mo 2FeB2 coatings were studied. It is found that the height and width of the coating increases and the dilution rate decreases gradually when the thickness of the powder is increased. The thickness of the powder do not affect the phase composition of the coating, but the main phase composition present in the coating helps to improve the hard‐ ness, wear resistance and other properties of the coating. The microstructure of the coating is observed that the number of dendrites shows a trend of first increasing and then decreasing with the increase of the powder thick‐ ness, and the size of the dendrites first remains the same and then decreases, and the gap of dendrites is smaller than the other two thicknesses when the powder thickness is 1.0 mm. The metallographic spotting test and element mapping results show significant elemental segregation in the coating. Microhardness test shows that the increase in the thickness of the spreading powder is beneficial to improve the average hardness of the coating. Wear test show that the increase in the thickness of the spreading powder is beneficial to improve the wear resistance of the coating. It is found that 1.0 mm is the best powder thickness selection by analyzing the macroscopic morphology, microstructure, hardness and wear resistance of different powder laying thicknesses and integrating the actual de‐ mand and economic benefits. 2024 Vol. 34 (01): 102-110 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 111 Microstructure and wear resistance of FeCrCoNi coating on automotive stainless steel surface synthesized by laser in situ Hot! ZHANG Liansong，SU Tao，SHEN Siming DOI: 10.13228/j.boyuan.issn1006-6543.20230070 In order to improve the surface hardness and wear resistance of 316 stainless steel for vehicle used, FeCrCoNi high entropy alloy coating were prepared on the surface of 316 stainless steel by laser cladding in situ synthesis. The phase composition, element distribution, microhardness and wear resistance of FeCrCoNi high entropy alloy coating were studied. The results show that the FeCrCoNi high entropy alloy coating prepared in situ has no cracks, pores and other defects, and has good metallurgical bonding with the substrate. FeCrCoNi high entropy alloy coating is composed of a single FCC phase with dendrite and interdendrite structures. All elements are evenly distributed without obvious segregation. The microhardness of FeCrCoNi high entropy alloy coating is 287.3 HV, which is about 50% higher than that of 316 stainless steel substrate. The average friction coefficients of FeCrCoNi high entropy alloy coating are 0.377 and 0.438, respectively, and the wear rate of FeCrCoNi high entropy alloy coating is 70% lower than the wear rate of 2.27×10-5 mm3/N·m and 6.17×10-5 mm3/N·m, respectively. The wear mechanism of FeCrCoNi high entropy alloy coating is abrasive wear. 2024 Vol. 34 (01): 111-116 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 117 Research status and prospect of high entropy alloy composite coatings Hot! DONG Tianshun，LIU Jianhui，LU Pengwei，FU Binguo，LI Guolu，MA Qingliang DOI: 10.13228/j.boyuan.issn1006-6543.20220230 High-entropy alloy coatings can bring out the excellent comprehensive performance of high-entropy alloy on the basis of economy and practicality, but its strengthening method is mainly solid solution strengthening, and the strengthening effect has great limitations, so it is necessary to introduce hard particles into high-entropy alloy coatings to achieve composite enhancement, so as to obtain a high-entropy alloy composite coating with better performance. This paper reviews the main techniques for preparing high-entropy alloy composite coatings, such as laser melting technology, plasma melting technology and argon arc melting technology, and focuses on the current research status of direct addition and in-situ synthesis of hard particles to enhance high-entropy alloy composite coatings, analyzes their organization and structure, and discusses the effects of hard particles on high-entropy alloy composite coatings in terms of hardness, wear resistance, corrosion resistance and high-temperature oxidation resistance, respectively. Finally, the problems in the research of high-entropy alloy composite coatings are summarized . 2024 Vol. 34 (01): 117-123 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 124 Research progress on hot extrusion process of P/M superalloy Hot! SHI Yingnan，SUN Shaobin，QU Jinglong，LIU Mingdong，RONG Kun，JIA Jian DOI: 10.13228/j.boyuan.issn1006-6543.20220198 The development and application of hot extrusion process for P/M superalloys in Europe and US were summarized. The research progress of hot extrusion process for P/M superalloys in China was described. The selection principles of extrusion process parameters for René 95, René 88DT and FGH4096 alloys were introduced. The influence of extrusion process parameters (extrusion ratio, extrusion speed, extrusion temperature, etc.) on the extrusion forming, microstructure and properties of P/M superalloys was emphatically expounded. The evolution behavior of non-metallic inclusions in P/M superalloys during hot extrusion was clarified. 2024 Vol. 34 (01): 124-133 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 134 Research progress of combustion assisted materials and technologies for aluminium powder Hot! GUO Huili，ZHANG Weipeng，HUANG Yafeng，ZHANG Junlin，ZHAO Dongkui DOI: 10.13228/j.boyuan.issn1006-6543.20220200 Aluminum powder is the most commonly used metal fuel in the explosives and propellants industry. How to make aluminum powder react as completely as possible in explosives and propellants has always been a difficult problem to solve. The combustion-assisted materials and technologies for aluminum powder are systematically reviewed and the different mechanism of promoting the combustion of aluminum powder is analyzed in this paper. Ammonium perchlorate(AP), fluorine-containing materials, nitro-containing compounds, azide-based materials, etc. have significant auxiliary effects on the oxidation of aluminum powder, and the aluminum-containing composites prepared by self-assembly process can help aluminum powder react completely more effectively. 2024 Vol. 34 (01): 134-139 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 140 Research progress of combustion assisted materials and technologies for aluminium powder Hot! LI Youyu，YU Li，GAO Yang DOI: 10.13228/j.boyuan.issn1006-6543.20230042 Titanium alloy has the characteristics of high strength, lightweight, and high temperature resistance, making it a promising aerospace structural material. The traditional mechanical manufacturing process is difficult and costly, which limits the application of titanium alloys. Additive Manufacturing (AM), as an emerging advanced manufacturing technology, can produce metal components with high three-dimensional accuracy through layer by layer machining, providing near net shape machining for titanium alloys. This article first introduces the preparation technology of spherical titanium alloy powder, including Plasma Rotating Electrode Atomization Process (PREP), Electrode Induction Gas Atomization (EIGA), Plasma Atomization (PA), and Plasma Spheroidization (PS). The preparation technology and advantages and disadvantages of four spherical titanium alloy powders are compared, as well as their applications in aviation additive manufacturing, including Laser Selective Melting (SLM). The application characteristics and development trends of different titanium alloy powder preparation technologies in aviation additive manufacturing are summarized, such as Electron Beam Selective Melting (EBSM) and Laser Melting Deposition (LMD). It is pointed out that the key to the future development of spherical titanium alloy additive manufacturing is the preparation of low gap titanium powder. High precision, high efficiency and large scale of additive manufacturing equipment will be the future development trend. 2024 Vol. 34 (01): 140-147 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 148 The status and development of copper-based friction plates Hot! YANG Shuiyu，ZHOU Huanhui，LI Yansen，XU Chengfa DOI: 10.13228/j.boyuan.issn1006-6543.20230046 Heavy-duty and special vehicle transmissions generally use friction plates based on copper-based powder metallurgical materials. With the development of the transmission to high speed, high torque, heavy load, etc., the problems of inadequate performance of traditional friction plates are gradually leaking out, such as friction layer peeling, core plate fracture. Aiming at the problems that are becoming increasingly evident in copper-based friction plates, the development process of friction discs and the current application status of copper-based friction discs are analyzed, their composition and material composition are introduced, and the common failure forms and requirements of friction discs are explained. Further, the targeted strategies are proposed in terms of composition design, manufacturing process, structural design, post-treatment strengthening, and so on. It is pointed out that the optimization of multi-process coupling and the resrarch of new environmentally friendly composite friction plates will be an important direction for the development of friction plates. 2024 Vol. 34 (01): 148-153 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 0 ) 154 Effect of TiO 2 doping on properties of MnZn power ferrite Hot! ZHU Jiangpo，WANG Hongjian，XIA Mingyang，XING Bingbing DOI: 10.13228/j.boyuan.issn1006-6543.20230007 Low power MnZn power ferrites were prepared using traditional oxide ceramic methods. The effects of TiO2 doping on the microstructure, saturation magnetic induction, initial magnetic permeability, and power loss of power ferrites were studied. The results show that adding an appropriate amount of TiO2 can improve grain uniformity, increase saturation magnetic induction strength, initial magnetic permeability, and reduce losses, especially at low temperatures. However, adding too much TiO2 can cause abnormal grain growth, decrease saturation magnetic induction strength, and worsen high temperature losses. When the TiO2 content is 0.25%, the ferrite sintered samples have uniform grain size, maximum saturation magnetic induction strength, and low loss. 2024 Vol. 34 (01): 154- [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 0 )

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