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Quick Search     Adv Search   2023 Vol. 33, No. 04 Published: 2023-08-10   1 Opportunities and challenges of China′s PM parts industry under the target of“carbon peak and carbon neutralization” Hot! CAO Yang DOI: 10.13228/j.boyuan.issn1006-6543.20230107 The automotive industry is one of the most important markets and main applications of new technolo‐ gies for worldwide powder metallurgy industry. This article introduces the development situations of China′s pow‐ der metallurgy industry, and briefly introduces the developments of auto PM parts market and home appliance PM parts market in recent years which are the most important markets for powder metallurgy industry in China. It also briefly introduces the development trend of the global automobile industry responding climate changes, as well as the development of new energy vehicles in China. The concept of“powder metallurgy+”process is put forward based on the basic understanding of PM as a“green”technology in PM associations of Europe and Unit‐ ed States, and it is compared that of the raw materials utilization rate and energy consumption per weight finished products between“powder metallurgy+”and other metal processing processes on the basis of actual measure‐ ment in this article. The results indicate that the“powder metallurgy+”process is a more resource-saving“green manufacturing”technology. The opportunities and challenges are given for developing China′s powder metallur‐ gy parts industry under“carbon peaking and carbon neutrality”target. 2023 Vol. 33 (04): 1-6 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 7 Preparation and mechanical properties of a 7075/TC4 composite material Hot! DONG Zhiyan，ZHAO Haidong，YANG Chao，ZHANG Weiwen，WANG Zhi DOI: 10.13228/j.boyuan.issn1006-6543.20220186 With the rapid development of aerospace and rail transit, single metal material is difficult to meet the requirements of light weight and high strength. Heterogeneous composite materials combined with two or more metal materials can obtain a good combination of strength and toughness. 7075 aluminum alloy has high strength and low density, and TC4 titanium alloy is the most widely used titanium alloy with both strength and toughness. Therefore, 7075 aluminum alloy and TC4 titanium alloy are combined to obtain bimetallic composites with excel‐ lent properties.In this paper, TC4 titanium alloy honeycomb topological structure preform was prepared by Selec‐ tive Laser Melting technology, and 7075 aluminum alloy melt was infiltrated at 700/750/800 °C by vacuum pres‐ sure infiltration to obtain 7075/TC4 composites. The area of 7075 aluminum alloy in 7075/TC4 composites is main‐ ly composed of fcc-Al, Al3Fe and MgZn2. The region of TC4 titanium alloy is mainly composed of lamellar α phase and β phase. The interface layer is mainly composed of Al3Ti, and its thickness increases from 6 μm at 700 °C to about 300 μm at 800 °C. When the infiltration temperature is 750 °C, the properties of the composites are the best, and the yield strength, compressive strength and fracture strain are (755±5) MPa, (1 136±12) MPa and 23%±1.5%, respectively. The fracture behavior of the composite material is as follows: the crack initiates at the grain boundary of the aluminum alloy region. With the increase of load, the cracks in the aluminum alloy area expand, and the cracks initiate at the defects of the interface and the titanium alloy area. With the further increase of the load, cracks in the aluminum alloy region expand to the interface, and connect with the cracks in the interface and the ti‐ tanium alloy structure region, resulting in material failure. At different infiltration temperatures, the phase composi‐ tion of the composite 7075 aluminum alloy region, TC4 titanium alloy region and interface region is similar. How‐ ever, the thickness of the interface layer increases with the increase of infiltration temperature. With the increase of infiltration temperature, the compressive strength and compressive plasticity of the composites first increase and then decrease, and reach the best at 750 °C. The grain boundary second phase, infiltration defects and SLM defects have adverse effects on the properties of the composites.the 2023 Vol. 33 (04): 7-14 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 15 Influence of vacuum sintering temperature on microstructure and properties of austenitic stainless steel containing Sn Hot! QIN Qun，LIU Xinyu，WANG Tianguo DOI: 10.13228/j.boyuan.issn1006-6543.20230011 Vacuum sintering makes it easier to expel gas from the pores of stainless steel powder compacts, there‐ by improving the density of stainless steel sintered materials. The sintering process has a significant effect on the density mechanical properties, corrosion resistance, and other properties of powder metallurgy 304 austenite. This article uses vacuum sintering to prepare powder metallurgy 304 austenitic stainless steel, and adds a certain amount of sintering additive Sn to study the effect of vacuum sintering temperature on the microstructure and properties of 304 stainless steel. The results show that when the sintering temperature is below 1 270 ℃, the activity of atoms is insufficient, the diffusion degree is weak, and there are many internal pores in the sintered body, with irregular and uneven distribution of pores and low density. When the sintering temperature is 1 270 ℃, the number of pores in the microstructure of the sample is relatively small, the pore size is small, and the shape is more regular. At this sintering temperature, the dimples in the fracture surface of the sample are deep and uniformly distributed, and the dimples are connected in a network form. The number of pores is small, and the distribution is uniform, with a tendency to spheroidize. When the sintering temperature is 1 270 ℃, the activi‐ ty of atoms increases. Due to the addition of sintering additive Sn, a certain amount of liquid phase appears dur‐ ing the sintering process. Under the surface tension of the liquid phase, the diffusion speed of metal atoms accel‐ erates, and solid particles are rearranged to achieve dense arrangement. This causes the pores generated in the sin‐ tered body to be filled by the liquid phase, reducing the number of pores in the sintered body, and significantly increasing the density of sintered stainless steel. The hardness and tensile strength reached their maximum values, which were 7.31 g/cm3, 62.23HRB, and 363.34 MPa, respectively. When the sintering temperature exceeds 1 270 ℃, the number of pores in the microstructure of the sintered sample increases, the size of the pores increas‐ es, and the density, hardness, and tensile strength of the sintered sample decrease. When the sintering temperature is 1 270 ℃, the self corrosion current of 304 stainless steel sintered sample is the smallest and has the best corro‐ sion resistance performance. As the sintering temperature increases, the corrosion current density of the sample decreases, and the corrosion resistance of the sample improves. The main reason is that as the sintering tempera‐ ture increases, a higher sintering temperature is conducive to the diffusion of atoms and the generation of liquid phase. The porosity of the sample decreases, the density increases, and the corrosion resistance of the sample is improved. The appropriate sintering temperature increases the liquid phase in the sintered body of 304 stainless steel, fully metallurgical bonding between particles, reduces the number and size of pores, and improves the alloy‐ ing degree of the sintered sample, which is conducive to the densification of the 304 stainless steel sintered sam‐ ple, and improves the mechanical properties and corrosion resistance of the sample. 2023 Vol. 33 (04): 15-21 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 22 Study on the preparation process of Al-doped-ZnO (AZO) ceramic target Hot! TANG Peixin，Lü Zhoujin，CHE Lida，WU Zhanfang DOI: 10.13228/j.boyuan.issn1006-6543.20220173 The AZO target is an alloy target of transparent conductive zinc oxide that exhibits excellent conduc‐ tivity and transparency, which has wide application in various fields, including solar cells, liquid crystal displays, and optoelectronic devices. In this paper, Al-doped-ZnO (AZO) ceramic target was prepared by powder mixing+ cold isostatic pressing+non-pressure sintering. The mixed powder was obtained by ball milling and spray drying. The effects of different sintering temperatures on the properties of AZO ceramic targets were studied, and the op‐ timal process parameters were determined. The results show that the AZO target with excellent properties can be prepared by spray drying powder + cold isostatic pressing + non-pressure sintering at 1 300 ℃, in which the den‐ sity is 99%, average grain size is 20 μm, resistivity is 10-3 Ω·cm, and contains a small amount of ZnAl2O4 phase. The hot isostatic pressing experiment find that hot isostatic pressing can increase the density of the sintered billet from 97.2% to 100%, reaching the theoretical density. The ultra-high density target material can withstand higher power, long-term sputtering without cracking, and can significantly improve sputtering efficiency. 2023 Vol. 33 (04): 22-26 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 27 Morphology control of small particle size product Ni0.55Co0.50Mn0.40(OH)2 Hot! LIU Jiying，LIU Fei，YANG Yongsheng，MI Xixue，KANG Mei，LI Peng DOI: 10.13228/j.boyuan.issn1006-6543.20220091 The effects of gas, solid-liquid ratio, PH, batch separation time and nucleation time on the morphology of Ni 0.55Co0.50MN0.40(OH)2 were studied by co-precipitation experiment. The results show that when the PH value is 10.5~10.6, the ratio of solid to liquid is 8% , the batch separation time is 1 t≤m≤2 t, the separation reactor is not needed and the nucleation time is 1.5 h, Ni0.55Co0.50MN0.40(OH)2 with good morphology can be synthesized. 2023 Vol. 33 (04): 27-31 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 32 Material composition and structure optimization for sinter-brazing ferrous powder metallurgy components Hot! HUANG Yongqiang，SHEN Xiaoping，KANG Limei DOI: 10.13228/j.boyuan.issn1006-6543.20210171 Excellent welding performance depends on the base material composition, solder composition and weld structure. The optimal combination group of base metal with Fe-3.5%Ni-0.5%Mo-2.5%Cu-0.7%C and filler metal with Cu-32%Ni-18%Mn-1.5%B-2%Si-3%Fe was obtained by orthogonal experiment. The structure of the welding joint is optimized to achieve the maximum welding strength of 84 MPa when the weld depth is 0.3 mm. In addition, the connection mechanism of the welding area is studied from a microscopic perspective through pore distribution and metallographic analysis. 2023 Vol. 33 (04): 32-37 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 38 Investigation on precision grinding of PcBN Inserts by vitrified diamond grinding wheels prepared by different processes Hot! CHEN Jianli，LIU Yibo，LIU Yang，WANG Xiongfei，TIAN Likun，KONG Shuaifei DOI: 10.13228/j.boyuan.issn1006-6543.20220106 The vitrified bond and related grinding wheel were prepared by melt-quench water method and sol-gel method respectively. The effects of preparation technology on the phase, linear expansion coefficient, bending strength and diamond dispersion of the binder were studied. The machining performance of ceramic bond pre‐ pared by different technology on PcBN tool was studied. The results show that SiO2 crystals precipitate in the binder prepared by melt-quench water method, and the coefficient of SiO2 crystals increases the thermal expan‐ sion coefficient and decreases the bending strength of the binder. The agglomeration of M2.5/5 diamond in fusion-quenched water bonding method reduces the holding force of the binder on diamond and increase the sur‐ face roughness of PcBN tool grinding. 2023 Vol. 33 (04): 38-43 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 44 Effect of solution treatment on microstructure and properties of P/M superalloy FGH91 Hot! LI Kemin，CUI Yangyang，ZHU Xiaolei，WANG Ningbo，JIA Jian，LIU Mingdong DOI: 10.13228/j.boyuan.issn1006-6543.20220210 The effect of solution treatment on the microstructure and properties of FGH91 was studied. The re‐ sults show that when FGH91 alloy is treated at a solution temperature below γ ' solidus, with the increase of solu‐ tion temperature, the grain size of FGH91 alloy has no obvious change, the content of primary γ 'phase decreases. The size and content of secondary γ' phase increase gradually with the increase of solution temperature. The hard‐ ness and tensile strength at room temperature and high temperature tensile strength of FGH91 alloy increase with the increase of solution temperature. With the decrease of cooling rate after solution treatment, the grain bound‐ ary bending amplitude and frequency increase, and the stress rupture life and creep property of FGH91 alloy is improved. 2023 Vol. 33 (04): 44-48 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 49 Study on preparation and performance of copper-based brake friction plate Hot! SUN Haiying，GAO Wenqiang，CHEN Hua，LI Jing，PAN Yuan′an DOI: 10.13228/j.boyuan.issn1006-6543.20210162 In this paper, the copper-based brake friction plate is manufactured by powder metallurgy technology. The main components are Cu, Fe and graphite. The morphology of sintered and worn microstructure was ana‐ lyzed by scanning electron microscope, the phase structure of the samples was analyzed by X-ray diffractometer, and the friction and wear properties of the samples were tested by MM-W1B vertical universal friction and wear testing machine. The results show that the average density of copper brake material is 5.83 g/cm3, the porosity is 24.6%, the compressive strength is 108 MPa, and the average hardness is 84 HV, which meet the requirements of brake friction plate. Under dry friction conditions, the friction coefficient can reach 0.31-0.45 when the rotation speed ranges from 200 r/min to 600 r/min, and the main wear mechanisms are abrasive wear and oxidation wear. Under the condition of lubricating friction, the higher the temperature, the greater the friction coefficient, the friction coefficient is less affected by rotational speed. 2023 Vol. 33 (04): 49-53 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 54 Comparative study on performance of different epoxy resin composite coatings on copper tube surface Hot! SHI Xinli，ZHANG Liu DOI: 10.13228/j.boyuan.issn1006-6543.20220169 To find the heat exchange coil of air source heat pump with the best performance, SiC powder, gra‐ phene and spherical graphite with different volume concentrations were added to the coating on the surface of the copper tube, and the water-based epoxy resin coating was used as the comparison benchmark. The effects of dif‐ ferent filler types and filler concentrations on heat dissipation performance, anti-frosting performance and corro‐ sion resistance performance of the specimens were studied respectively. The test results show that the perfor‐ mance of the coating is improved with the addition of filler. For the SiC filler coating, the heat dissipation, antifrosting and corrosion resistance all increase with the increase of volume concentration. For the graphene filler coating, with the increase of volume concentration, the anti-frosting performance is improved, but due to the ag‐ gregation of molecules, the heat dissipation and corrosion resistance increase first and then decrease. For the spherical graphite filler coating, the heat dissipation and anti-frosting properties increase with the increase of vol‐ ume concentration, and same as graphene, the corrosion resistance performance shows a trend of rising first and then falling. Through the comprehensive comparison of three different fillers, the performance of spherical graph‐ ite is better than other fillers in terms of anti-frosting and corrosion resistance performances, and in terms of heat dissipation, when the inlet water temperature is high, it is also superior to other test pieces. 2023 Vol. 33 (04): 54-60 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 61 Effect of Al content on microstructure and properties of B4C-CeB6/Al composites Hot! LI Tianyu，DONG Zhongqi，PAN Enbao，WANG Yang，ZHANG Baoyu，SONG Yu DOI: 10.13228/j.boyuan.issn1006-6543.20220137 The B 4C-CeB6/Al composites were prepared by mechanical alloying and cold-pressure microwave sin‐ tering. The microstructure and phase composition of the B4C-CeB6/Al composites were analyzed by using x-ray dif‐ fractometer and scanning electron microscope. The hardness of the materials was measured. The microstructure evolution law of the B 4C-CeB6/Al composite was studied by the addition amount of Al. The results show that the B 4C-CeB6/Al composite powders are mechanically alloyed during ball milling, and the powders are columnar. The phase composition of the B4C-CeB6/Al composites varies with Al addition, and the main phases are B4C, CeB6, Al 2O3, Al3BC, Al5BO9 and CeBO3. With the increase of Al addition, the content of Al5BO9 and CeBO3 increases. The CeB 6 and Al3BC phase increase first and then decrease, and the hardness of the material increases first and then decreases. 2023 Vol. 33 (04): 61-65 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 66 Experimental study on selective laser melting process of nickel-based superalloy Hot! DUAN Xianyin，LONG Tao，CHEN Xinyue DOI: 10.13228/j.boyuan.issn1006-6543.20230014 IN718 alloy is of great interest currently, due to its extraordinarily excellent strength, corrosion resistance, and fatigue properties, which is the main material for manufacturing aero-engines with complex structures. As one of the most reliable and feasible additive manufacturing technologies, selective laser melting (SLM) can greatly shorten the manufacturing cycle and improve the utilization of materials. However, defects such as spheroidization, porosity and cracks often occur in the SLM process, reducing the quality of the SLMed parts. To improve the quality of SLMed parts, the effects of process parameters such as laser power, scanning speed and hatching space on the quality indexes of the SLMed parts and the sensitivity analysis of each process parameter were studied. The SLM process parameters of IN718 alloy were optimized. This paper conducted multi-groups of experiments with different laser powers, scanning speeds and hatch spacings, measuring the surface roughness, surface height difference, sphericity, surface melting width, microhardness and microstructure of the SLMed parts. Analysis of extreme differences was employed to process the data obtained to investigate the sensitivity of the process parameters to the above factors. When the laser power is 180 W, the scanning speed is 800 mm/s, and the hatching space is 0.10 mm, the SLMed part with the surface roughness of 32 μm and the sphericity of 3.623% are obtained. While with a laser power of 160 W, a scanning speed of 600 mm/s and a hatch spacing of 0.06 mm, the surface roughness increases to 177 μm and the sphericity decreases to 1.007%. Irregular pores are observed in the microstructures of the SLMed parts with a laser energy density of 32 J/mm3, while spherical pores are observed in the microstructures of the SLMed parts with a laser energy density of 83 J/mm3. Among the preset process parameters, for the surface roughness and the sphericity, the influence of scanning speed is the greatest, followed by laser power, and the influence of lap spacing is the least. Microhardness increasing and then decreasing along the build direction, shows a trend similar to a normal distribution. Irregular pores occur in the molten pool at low laser energy densities, while spherical pores occur at high laser energy densities, and almost no obvious defects inside the molten pool at moderate laser energy densities. This study could help to improve the surface quality of selective laser melting parts of IN718 alloy by optimizing the process parameters. 2023 Vol. 33 (04): 66-74 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 75 Effect of laser in situ synthesis NbC on microstructure and wear resistance of 316L stainless steel cladding for wind turbine Hot! ZHAO Qun，ZHAO Jinfang，ZHU Shuang，WANG Lin DOI: 10.13228/j.boyuan.issn1006-6543.20230020 In order to improve the hardness and wear resistance of 316L stainless steel coating, 316L-10%Nb- 5%Cr3C2 metal matrix composite coating was prepared on 304 stainless steel surface by laser cladding technology. The phase composition, microstructure, element distribution, microhardness and wear resistance of the composite coating were studied systematically. The results show that the composite coating consists of γ -Fe, Fe-Cr solid solution, NbC ceramic particles and Cr7C3. The microhardness of 316L-10%Nb-5%Cr3C2 composite coating is significantly higher than that of 316L coating, which is about (394±10.7) HV0.3, about 1.65 times of 316L coating. The wear test shows that the wear resistance of the composite cladding is about 2 times higher than that of the 316L coating under dry sliding condition. The wear mechanism of composite cladding layer is abrasive wear. 2023 Vol. 33 (04): 75-80 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 81 Microstructure and mechanical properties of （ZrH2+TiH2）/Al-Cu-Mn alloy processed by selective laser melting Hot! XU Xiaopeng，HUANG Weidong，QIN Shuaishuai，HUANG Xu，HE Dongdong，WANG Lu DOI: 10.13228/j.boyuan.issn1006-6543.20220095 To eliminate the thermal crack of Al-Cu alloy due to its wide solidification interval and improve its mechanical strength. The ZrH2+TiH2/Al-Cu-Mn composite powder was prepared by mechanical mixing and used for selective laser melting. The effects of ZrH2-TiH2 on the microstructure and mechanical properties of Al-Cu- Mn alloy were studied by means of optical microscope, SEM, EDS, hardness tester and tensile test.The results show that highest density is obtained when the laser energy density is 120 J/mm3. The addition of ZrH2-TiH2 into the Al-Cu-Mn alloy effectively promoted the columnar-to-equiaxed transition and grain refinement, the hot cracks are eliminated after ZrH2-TiH2 addition. Compared to the Al-Cu-Mn alloy, the ZrH2-TiH2 added alloy exhibits increased properties: the microhardness increases by 16.5%, the ultimate strength reaches 356.5 MPa, and the elongation is 8.8%. After solution treated at 540 ℃ for 1 h and aged at 185 ℃ for 10 h, the ultimate strength of the sample is further increased to 460.9 MPa, and the elongation reaches 11.4%. The addition of ZrH2 and TiH2 can effectively eliminate the thermal crack in the forming process of Al-Cu alloy and improve the mechanical properties of the alloy. 2023 Vol. 33 (04): 81-89 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 90 The microstructure and high cycle fatigue property of selective laser melting TA15 titanium alloy Hot! CAI Xiaoye，BAI Bing，HU Jiaqi，DONG Dingping，CI Shiwei DOI: 10.13228/j.boyuan.issn1006-6543.20220115 Based on the test and analysis of static mechanical properties of TA15 titanium alloy samples formed by selective laser melting, the fatigue properties of TA15 titanium alloy samples formed by selective laser melting at room temperature were studied and analyzed. Tensile properties, impact properties and fatigue properties of TA15 titanium alloy samples at room temperature were tested by universal testing machine, impact testing machine and fatigue testing machine. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to analyze the microstructures of the cross-sectional and longitudinal sections, as well as the tensile and fatigue fractures of the samples. The research shows that the cross section presents a typical checkerboard lattice structure, and the longitudinal section distributes β columnar crystals penetrate through multiple deposition layers and grow epitaxially, and acicular martensite is staggered inside the columnar grains. The tensile strength of the transverse and longitudinal samples after annealing treatment, the strength and yield strength are lower than that of the as-deposited samples, and the elongation, shrinkage and impact strength are significantly improved, and they are all better than the TA15 bar index. The fatigue life data has a certain dispersion, which is the main reason for the fatigue dispersion. It is a selective laser melting and forming process. The metal powder is rapidly melted and cooled under the action of a high-energy laser, and defects such as poor overlap, pores, and unmelted powder appear randomly inside the part. The depositional cross section of TA15 titanium alloy formed by selective laser melting presents a typical checkerboard lattice structure. The longitudinal section is distributed with β columnar crystals growing epitaxial through several sedimentary layers. The columnar crystals are interleaved with acicular martensite. The ratio of length to width of primary and secondary α phases in annealed microstructure decreases continuously, and the spicules are coarsened continuously to form strip. After being held at 850 ℃ for 2 h, the tensile strength and yield strength of the transverse and longitudinal samples of TA15 titanium alloy decrease, while the elongation, shrinkage and impact strength of the samples are significantly increased, which are better than those of TA15 sheet. Fatigue life data of annealed TA15 titanium alloy in selective laser melting forming (stress ratio R=0.06, Kt=2.5) have a certain dispersion. The main reason for the fatigue dispersion is the rapid melting and cooling of metal powder under the action of high energy laser. Defects such as poor lap joint, air hole and unmelted powder appear randomly in the parts. 2023 Vol. 33 (04): 90-96 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 97 Effect of selective laser melting parameters on microstructure and mechanical properties of CoCrWMo alloy Hot! ZHAO Xiaohao，ZHANG Peng，PAN Feifei，GUO Shaoshuai，LIU Like，LIANG Shujin DOI: 10.13228/j.boyuan.issn1006-6543.20220076 Selective Laser Melting is widely applied to dental restoration. In this paper, different sets of laser power and varying scanning velocity were investigated. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Image Pro Plus (IPP) were exploited to analyze microstructure and constituent phases. Tensile testing was performed to evaluate corresponding performance. The prime set of parameters have been selected from 15 parameter sets. The prime set possessed excellent combination of strength and ductility while the elongation is up to 20% with dimples characterization. The ultimate tensile strength and yield strength was (1 066±33) MPa and (849±30) MPa, respectively. The microstructure is composed of γ -fcc phase, of which the percentage is over 95%. During printing, most of porosity surpassed 0.2% in relative low energy density（19.5~26.0）J/mm3. On the contrary, high energy density（26.0~36.5）J/mm3 tends to obtain lower porosity which is below 0.1%. The experiment displays porosity is deeply corresponding to printing parameters, like laser power and scanning velocity, rather than energy density. 2023 Vol. 33 (04): 97-105 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 106 A study on gas-powder two-phase flow of Ni-based coatings by laser cladding based on response surface methodology Hot! CHU Mengya，LIAN Guofu，FENG Meiyan，CHEN Changrong，LAN Ruqing DOI: 10.13228/j.boyuan.issn1006-6543.20220081 A simulation scheme was designed with response surface methodology (RSM) to reveal the influence law of the interaction of input parameters in laser cladding on the convergence of powder flow as well as improve powder utilization in the cladding process. Regression equation was established by fitting functional relationship between the input parameters and the characteristic parameters of powder flow to present the influence law of the input parameters and their interaction on average powder concentration and powder-spot diameter on the substrate. The research result show that average powder concentration on the substrate is significantly affected by airflow, powder-feeding voltage, nozzle′s working height, the interaction term of airflow and nozzle′s working height, the interaction term of powder-feeding voltage and nozzle′s working height, and the quadratic term of nozzle′s working height. The airflow and working height of the nozzle significantly affect the diameter of the powder spots on the substrate. Average powder concentration on the substrate decreases with increased airflow and increased nozzles′ working height, and increases with increased powder-feeding voltage. The diameter of the powder spots on the substrate increas with increased nozzle′s working height and increased airflow. The optimization goal referred to the maximum average powder concentration on the substrate and the minimum powder spot diameter. The simulated values of average powder concentration on the substrate and powder-spot diameters are compared with the predicted values, and the errors are 6.6 and 1.74%, respectively. The work can provide theoretical guidance for the parameter selection of laser cladding technology in industrial applications. 2023 Vol. 33 (04): 106-114 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 115 Study on the influence of powder size and process parameters on the microstructure and properties of NbC cladding layer Hot! YUE Kun，LIAN Guofu，HUANG Xu，FENG Meiyan，LAN Ruqing DOI: 10.13228/j.boyuan.issn1006-6543.20220140 In this study, Nb and B4C particles with different particle sizes were prepared on 45 steel surface to synthesize NBC in situ. The effect of different particle size and process parameters on the microstructure evolution and microhardness of the composite coating was studied. The central composite design module of response surface method was used to analyze the influence of powder particle size, laser power, scanning speed and gas flow rate on the performance of composite cladding layer, and the mathematical model between process parameters and cladding layer hardness was established. The accuracy of the model was verified by variance analysis and model test. It is found that the phase composition of the cladding layer is not changed by changing the particle size of the powder, but the hardness of the cladding layer increases with the increase of the laser power and the particle size of the powder, and decreases with the increase of the scanning speed and the gas flow rate. The error rate between the predicted value and the actual value is 1.4 %. The research results provide a theoretical basis for the prediction and control of cladding layer performance. 2023 Vol. 33 (04): 115-123 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 124 Study on preparation of high-performance ODS alloy via powder metallurgy Hot! ZHOU Zhihong，MA Jiao，PENG Jinyan，KANG Ruichao，YANG Shengbing，LI Weihang DOI: 10.13228/j.boyuan.issn1006-6543.20220027 Oxide dispersion strengthened alloy was one of the most promising materials in nuclear reactor materials. Thanks to the addition of a large number of evenly distributed nano oxides into the metal matrix, the alloy had good high-temperature mechanical properties. At the same time, ODS Fe matrix alloy adding a certain proportion of Cr and Al that will greatly improve the corrosion resistance. Since the comprehensive performance of ODS alloy prepared by powder metallurgy was better than that of melting method, ODS alloy was mainly prepared by powder metallurgy in recent years. This paper systematically summarized the recent preparation and sintering processes of various alloy powders, including the preparation of alloy powders by mechanical alloying, internal oxidation and hydrothermal-freeze drying, and the preparation of alloys by hot isostatic pressing, powder forging and spark plasma sintering. At the same time, in order to provide reference for the preparation of ODS alloys with excellent comprehensive properties, the current research results and existing problems of preparation processes were expounded. 2023 Vol. 33 (04): 124-131 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 132 Preparation and their adsorption of cadmium ions of S2- intercalated layered double metal hydroxides Hot! CHEN Ke，ZENG Qifei，ZENG Zhiwen DOI: 10.13228/j.boyuan.issn1006-6543.20220002 S2- intercalated layered double metal hydroxide adsorbents were prepared by ZnSO4, Ga(SO4)3, Al(OH)3, CH4N2O and N2S as raw materials. Nano-laser particle size analyzer, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the particle size, morphology and crystal form of the new adsorbents. The results show that the average particle size of ZnAl-2 is 57.4 μm, and its morphology is more spongy, while the average particle size of GaAl-3 is 71.7 μm with uniform morphology and thin walls. The adsorption performance of the four synthesized adsorbents for cadmium ions is as follows: with the extension of the adsorption time, the effect increases when the adsorption time reaches 60 min, the increase of the adsorption effect is not obvious when the adsorption time increases more, so the adsorption time is determined to be 60 min. The adsorption properties of the four synthesized adsorbents are: GaAl-3 > ZnAl-2 > GaAl-2 > ZnAl-2. 2023 Vol. 33 (04): 132-136 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 )

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