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Quick Search     Adv Search   2023 Vol. 33, No. 01 Published: 2023-02-10   1 Research status of cemented carbide powders based on additive manufacturing Hot! LI Xiaofeng，ZHAO Yuxia，GUO Zi′ao，LIU Bin，BAI Peikang，LIU Bin DOI: 10.13228/j.boyuan.issn1006-6543.20220188 Cemented carbides, composed of refractory metal carbide (WC, TiC, NbC, etc.) and metallic binder phases (such as Fe, Ni and Co), are prepared by powder mixing, pressing, and then sintering. However, the traditional powder metallurgy method is expensive to fabricate molds, and it is difficult to make complex parts. In contrast, additive manufacturing (AM, also named as "3D printing") adopts digital lamination processing technology that enables to achieve fast and precise forming. One of the most critical steps for achieving high-quality products is researching and developing cemented carbide powders suitable for additive manufacturing. At present, the preparation methods of cemented carbide powders for additive manufacturing are mainly divided into the following four categories: mechanical alloying, spherical WC surface coating technology, spray drying technology and plasma spheroidization technology. These four methods differ in fabrication principle, cost, and flexibility of forming method. Four common preparation methods mentioned above of cemented carbide powders fabricated by AM were reviewed, the physical characteristics and forming properties of the prepared powders were compared, and the principles of powder preparation, their respective advantages and disadvantages, and the suitable additive manufacturing process were analyzed, in order to promote the research and development of cemented carbide powders made by AM. 2023 Vol. 33 (01): 1-9 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 10 Non-isothermal reduction kinetics of biomass carbon-coated spherical iron oxide nanoparticles Hot! HAO Suju，LIU Zheng，JIANG Wufeng，BO He，GAO Yice，ZHANG yuzhu DOI: 10.13228/j.boyuan.issn1006-6543.20220055 The TG-DTA curve of carbon-coated spherical nano-iron oxide in N2 atmosphere was drew by high temperature comprehensive thermal analyzer. The thermogravimetric variation of carbon-coated spherical nano-iron oxide at different heating rates was analyzed. The reaction mechanism of carbon-coated spherical nano-iron oxide in N2 atmosphere was studied and its dynamic parameters were got. Ironic nitrate nonahydrate and urea were used as raw materials to control the formation of spherical nano-iron oxide by hydrothermal method, and carbonized biomass glucose by hydrothermal carbonization to prepare carbon-coated spherical nano-iron oxide. The kinetic parameters of carbon-coated spherical nano-iron oxide reduction were determined by mutual verification by Flynn-Wall-Ozawa method and Coats-Redfern method. Spherical nano-iron oxide was successfully prepared by hydrothermal method, and carbon-coated spherical nano-iron oxide was successfully prepared by hydrothermal carbonization using biomass glucose as carbon source. The reaction process of carbon-coated spherical nano-iron oxide under N2 atmosphere was determined by kinetic analysis, as well as its reaction activation energy and reaction model. The results show that the reaction between coated biomass carbon and nano-iron oxide can occur at 180 °C, the reduction temperature is reduced.With the increase of temperature, the CO generated by the reaction will continue to participate in the reaction, accelerating the reduction of spherical nano-iron oxide.The reaction activation energy is about 79.48 kJ/ mol, and the reaction model is a three-dimensional diffusion model. 2023 Vol. 33 (01): 10-16 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 17 Study on the friction and wear properties of selective laser melted Al-Cu-Mg alloy Hot! YAN Hao，WANG Shixin，LI Xiaofeng，WANG Jianhong，XU Hong，LIU Bin DOI: 10.13228/j.boyuan.issn1006-6543.20220022 Aluminum alloys, which have the advantages of low density, high specific strength, and good corrosion resistance, are widely used in aviation, shipbuilding, automobiles, and other fields. Selective laser melting forming (SLM) is a promising technology that can fabricate complex parts at one time. In this study, the friction and wear properties of Al-Cu-Mg alloy fabricated by selective laser melting (SLM) were studied and compared with those of a cast ZL205A alloy with a similar composition. The results show that the SLM process can refine the alloy grains, change the size and distribution of Al2Cu, and make the grains smaller and more uniform. Compared with the cast ZL205A alloy, the wear rate and friction coefficient of the SLM-fabricated Al-Cu-Mg alloy decreased in varying degrees. SLM-fabricated Al-Cu-Mg alloy has the best wear resistance in cross section, followed by longitudinal section, and cast ZL205A has the worst wear resistance. The wear mechanisms of SLM-fabricated Al-Cu-Mg alloy are different under varying loads: the wear mechanisms at low load are mainly abrasive, and a little adhesive and plastic extrusion wear; the wear mechanisms under medium load are abrasive, adhesive and oxidation wear; the wear mechanisms under high load are mainly a combination of delamination, adhesive and oxidation wear. 2023 Vol. 33 (01): 17-23 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 24 Effect of copper powders on microstructure and properties of the MIM tungsten-copper alloy Hot! LIN Chihao，HU Ke，WANG Minghui，LEI Jiuhuai，LIN Bo DOI: 10.13228/j.boyuan.issn1006-6543.20220021 Metal injection molding (MIM) technology was adopted to prepare tungsten-copper alloy. Particle size and particle shape of the selected copper powders was quantitatively characterized by image analysis technology. The influence of the copper powders on the microstructure and properties of MIM tungsten-copper alloy was investigated in detail. By comparing，the characteristic parameters such as particle size, particle size distribution width, aspect ratio, roughness, outgrow and bluntness of the copper powders, the particle sizes of the crushed copper (CCu) powders and the water atomized copper (WCu) powders were much smaller than that of the reduced copper (RCu) powders, however the CCu powders exhibited wider particle size distribution and better regularity, surface smoothness and dispersion microstructure than the WCu powders and RCu powders. With tungsten powder blended with the CCu powders as raw materials, the tungsten-copper green parts were prepared by MIM showed high density and few defects. After sintering, the tungsten-copper alloy has the best microstructure and properties, with a density of 96.2%, a hardness of 235 HV, a bending strength of 1 200 MPa, a thermal conductivity of 128 W/(m·K) and an electrical conductivity of 30%IACS. 2023 Vol. 33 (01): 24-30 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 31 Effect of powder preparing method on microstructure and performance of Inconel718 alloy powder Hot! WANG Qingxiang，ZHU Zhen，LI Xin，WU Hao，ZHANG Peng DOI: 10.13228/j.boyuan.issn1006-6543.20220040 Inconel718 alloy was studied, and the metal spherical powder was prepared by plasma rotary electrode method (PREP) and gas atomization (VIGA), and the effects of different powder methods on microstructure and component distribution before and after heat treatment were studied. The cooling speed corresponding to the two powder floating methods was simulated by the flow heat exchange principle. The analysis results show that the Inconel718 alloy powder prepared by PERP method has a certain advantage in oxygen increment, sphericalness, and fluidity, and powder prepared by VIGA method facilitates improving the microharmal hardness of the powder, fine powder particle size. When the powder is subjected to the same heat treatment process, the microstructure change is the same, and Nb and Mo are analyzed. The results of the simulation calculations show that the fine-race-free powder is significantly higher than the powder corresponding to the PREP method, which is consistent with the performance data results corresponding to the experiment. 2023 Vol. 33 (01): 31-38 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 39 Microstructure and properties of powder metallurgy martensitic-austenitic composite steel Hot! LI Jingyu，WANG Yaomin，JIANG Feng，LI Yanguo，YANG Zhinan，ZHANG Fucheng DOI: 10.13228/j.boyuan.issn1006-6543.20220030 In recent years, the demand for high-strength-high-plasticity metal materials in the fields of automobiles and ships has been increasing. In order to obtain high-strength-high-plasticity metal materials, powder metallurgy technology plays an increasingly important role. In this study, the mixed metal powders of martensitic steel and austenitic steel with a mass ratio of 2:1 were sintered by spark plasma sintering (SPS), and the austenite phase was uniformly distributed in the martensite phase. The density of the sample is as high as 95.5%, and through the subsequent hot rolling treatment, the sintering quality of the composite steel is improved, and the density is increased to 98.9%.The yield strength, tensile strength, uniform elongation and total elongation of the clad steel after hot rolling are 960 MPa, 1 529 MPa, 6.7% and 6.7%, respectively. On the basis of hot rolling, cold rolling + short-time high temperature tempering treatment is introduced, and the performance of powder metallurgy composite steel is further improved. Among them, the clad steel cold-rolled at 30%-500℃ and tempered for 5 min has yield strength, tensile strength, uniform elongation and total elongation of 1 899 MPa, 1 964 MPa, 9.2% and 10.0%, respectively. 2023 Vol. 33 (01): 39-44 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 45 Study on the strip casting with high Ce content and its magnetic properties Hot! ZHANG Lele，GUO Yingjian，SHEN Peng，SUN Qisong，ZHU Minggang DOI: 10.13228/j.boyuan.issn1006-6543.20210062 The increasing demand for Nd-Fe-B magnets has resulted in a large backlog of rare-earth Ce metals indirectly. In order to improve the utilization rate of rare-earth Ce and reduce the production cost of Nd-Fe-B magnets, （Nd, Ce）-Fe-B magnets could be prepared by dual-main phase alloy method, which provided an effective way to solve the above problem. By exploring the composition of high Ce-contained strip casting and preparation process, Ce-Fe-B and（Nd, Ce）-Fe-B strip casting with good dendrites structure and almost no α-Fe phase have been successfully prepared. Among the prepared sintered magnets, the remanence of（Nd, Ce）-Fe-B magnets reaches to 11.33 kGs and that of Ce-Fe-B magnets reaches to 8.037 kGs, which provide data guidance for the later preparation of high performance and high Ce-contained dual-main phase sintered magnets. 2023 Vol. 33 (01): 45-50 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 51 Study on mechanical properties of high tungsten advanced shielding material Hot! ZHONG Jianqiang，SUN Changlong，WANG Meiling，MA Fei, HE Xueyi，WU Songling DOI: 10.13228/j.boyuan.issn1006-6543.20210165 The W-B4C/Al shielding material with excellent shielding performance of absorbing neutrons and shielding gamma rays were synthesized by the power metallurgic method. The effect of high tungsten content on the microstructure and mechanical properties of the W-B4C/Al shielding material were investigated. The results show that most of aluminum and tungsten in the W-B4C/Al exist in single phase in the selected range of tungsten content, and the WAl12 phase which effectively enhanced the material is presented. With the increase of tungsten content, the tensile strength (Rm) tends to decrease. The reduction of aluminum content weaks the bonding strength of the W-B4C/Al shielding material. When tungsten content is 80% (80W1.46B4C/Al), the prepared material exhibited the optimum comprehensive performance: the tensile strength (Rm) is 252 MPa, the yield strength (Rp0.2) is 209 MPa, the elongation (A50mm) is 2.1%, the impact toughness is 3.0 J/cm2 and the hardness (HV5) is 95.7. 2023 Vol. 33 (01): 51-55 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 56 Preparation and mechanical properties of low oxygen MHC alloy sheet Hot! ZHANG Xin，LIANG Jing，LIN Xiaohui，GAO Xuanqiao，XUE Jianrong，YANG Yichao DOI: 10.13228/j.boyuan.issn1006-6543.20220046 The low oxygen MHC alloy plates were prepared by powder metallurgy and hot rolling method. The microstructure, and mechanical properties of low oxygen MHC alloy rolled plates were studied by chemical analysis, metallographic analysis, hardness test, and tensile mechanical property test. The results show that molybdenum powder reduction, and vacuum sintering, the oxygen content in the alloy can be effectively reduced by adjusting C/Hf atomic ratio. The comparison of microstructure analysis and mechanical property test results of samples annealed at different temperatures, the recovery stage of the alloy is below 1 300 ℃. With the increase of annealing temperature, recrystallization begins at 1 300 ℃, the strength and hardness gradually decrease, and the plasticity increases. The recrystallization is completed at 1 600 ℃. The low oxygen MHC alloy with complete recrystallization has excellent plasticity. 2023 Vol. 33 (01): 56-59 [Abstract] ( 3 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 60 Effect of ball milling time on the powder morphology and properties of the RGO-Ni/Cu composites Hot! YAN Zhen，JIANG Fengyang，FU Chong，WANG Jinlong，LIU Xin，ZHANG Siyao DOI: 10.13228/j.boyuan.issn1006-6543.20220001 The RGO-Ni/Cu composites was prepared by electrostatic self-assembly, ball milling, and powder metallurgy to solve the problem of graphene structure damage in the ball milling. The effects of milling time on the morphology of the RGO-Ni/Cu powders and the microstructures、electrical conductivity、vickers hardness and antifriction performance of the RGO-Ni/Cu composite were studied. The results show that the morphology of the RGONi/ Cu powders changes from agglomerated to lamellar and then to fragmented with increasing the milling time, while the RGO-Ni powders of the two-dimensional wrinkles shape still retaining. The decentralized form of the RGO-Ni phase in the RGO-Ni/Cu composites is transformed from agglomerate distribution to stripe distribution with the increasing of milling time. The RGO-Ni/Cu composite has the best comprehensive properties at the milling time of 4 h and the coefficient of friction (COF) is 0.456. The wear mechanism of RGO-Ni/Cu composites is related to the formation degree of the graphene lubrication film. The formation of graphene lubricating film is affected by the relative density of the RGO-Ni/Cu composites. 2023 Vol. 33 (01): 60-66 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 5 ) 67 Microstructure and properties of extreme high speed Laser cladding 316L coating Hot! ZOU Yong，CHEN Mingying，WANG Qiulin，ZHANG Hong DOI: 10.13228/j.boyuan.issn1006-6543.20210053 Using extreme high speed laser cladding technology, 316L coating was prepared on 45 steel shaft. The microstructure of the coating was observed by scanning electron microscope (SEM), elemental and phase analyses were carried out by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the microhardness and wear resistance of the coating were tested. The results show that the extreme high speed laser cladding technology has a small spot diameter and a high overlap rate, so the flatness of the coating is high. The energy density is high (about 9× 104 W/cm2), and the powder is completely melted, so the coating has a high density. The volume of the melt is small, the heat and cold conversion speed is fast, the degree of undercooling ΔT is large, so the grain refinement is obvious. The middle and lower parts of the coating are composed of small dendrites produced by rapid solidification and interdendritic eutectic phases, the middle and upper parts grains gradually transform to equiaxed grains. At the overlap boundary and at the cladding layer/substrate interface, there is a large difference in grain size on both sides. The laser has a certain dilution effect on the substrate. The coating thickness is uneven, but it is well metallurgical bonded with the base material. The phase of the 316L coating is composed of γ -Fe, Cr0.19Fe0.7Ni0.11, Fe63Mo37. Due to fine grain strengthening and second phase strengthening mechanism, the average hardness of the 316L coating (634.12HV0.5) is 3.07 times that of the 45 steel substrate. The wear resistance is increased by 31.8%, and the main wear mechanism is abrasive wear. 2023 Vol. 33 (01): 67-72 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 4 ) 73 Effect of machining on residual stress on the surface of powder metallurgy beryllium Hot! HUANG Xugang，LI Zhinian，LIU Zhaogang DOI: 10.13228/j.boyuan.issn1006-6543.20220026 Beryllium has the characteristics of low density and high elastic modulus. It is used in aerospace structure. The residual stress on the surface of powder metallurgy beryllium during machining has a direct effect on the dimensional stability and service life of beryllium structural parts.In this paper, the residual stress on the surface of beryllium was measured by X-ray diffractometer, and the distribution of the residual stress along the surface under the processes of roughing, finishing and aging was measured. It is found that the residual stress of beryllium in powder metallurgy is compressive stress, and the residual stress is negatively related to the linear velocity and positively related to the feed rate, it can also effectively improve the uniformity of residual stress. 2023 Vol. 33 (01): 73-77 [Abstract] ( 4 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 78 Preparation and properties of porous nickel by space-holder-method Hot! WANG Hongwei，LI Yonghua，ZHENG Qingsong，CHEN Xiaolong DOI: 10.13228/j.boyuan.issn1006-6543.20220033 Porous nickel with high porosity and small pore was fabricated by powder metallurgy which was called space-holder-method and adding sodium chloride（NaCl）. The pore structures and mechanical properties were examined. The results show that by Adjusting the proportion of space-holder, sintering temperature and cooling time, porosity of sample was 60.84%~64.92%, the mean pore size was 0.20-8.80 μm with the proportion of over 20 μm occupying 92.0%~96.1%, compressive strength was 8.9-13.4 MPa. The mean pore size decreases correspondingly with increase of cooling time, but the compressive strength take on the trend of increase. 2023 Vol. 33 (01): 78-83 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 84 Microstructure and property analysis of W-7Cu-xNi alloy prepared by liquid phase sintering for power switch Hot! HAN Junfeng，MAYuechao，JIANG Ziming DOI: 10.13228/j.boyuan.issn1006-6543.20210020 In order to improve the comprehensive properties of W-7Cu alloy used for power switch, the w-Cu alloy containing different Ni contents was prepared by liquid phase sintering and mechanical ball milling.The microstructure, phase structure, hardness and thermal conductivity were measured by electron microscope, X-ray diffractometer, hardness tester and laser thermal conductivity tester.The results show that the larger size W particles are formed and the spacing between adjacent particles decreases with the increase of Ni content.The interface of W-Cu-4%Ni alloy forms a better wettability angle and obtains a continuous network distribution of copper phase, which improves the distribution uniformity of W-Cu microstructure. At this time, Ni element is completely dissolved with Cu phase. With the increasing of Ni content, the hardness and density of W-Cu alloy are higher, the thermal conductivity decreases, and the relative density increases. When 4% Ni is added, the density reaches 95.6%, the thermal conductivity decreases from 161 W/(m?K) to 96. 4 W/(m?K), and the alloy with higher density is obtained. 2023 Vol. 33 (01): 84-88 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 89 Synthesis and properties of cubic boron nitride superhard tool materials Hot! HUANG Jianna，ZHANG Jiexi，MAYulin DOI: 10.13228/j.boyuan.issn1006-6543.20210107 The synthesis law of cubic boron nitride superhard tool material (PCBN composite) was studied, and the microstructure and properties of PCBN composite were analyzed. PCBN composite sheets were synthesized by using CBN powder, WC powder and Co powder as raw materials on a hexahedral top press. The results show that when the sintering temperature is 1 750 ℃, the binding force of WC/Co binder to CBN particles is enhanced, and the wear ratio of the sample is the largest, which is 7 750. The PCBN composite piece sintered at 1 750 ℃ is made into a tool to continuously cut nodular cast iron. When the cutting mileage is 20 km, the wear amount (VB) of the rear face of the PCBN tool is the smallest, which is 0.272 mm. With the increase of temperature, the color deviation in the sample is less and less, the thickness distribution is more and more uniform, and the flatness is gradually improved, which indicates that increasing the sintering temperature is helpful to improve the flatness of the CBN polycrystalline layer in the composite. 2023 Vol. 33 (01): 89-93 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 94 Research on preparation of zinc oxide with different precipitants by hydrothermal method Hot! SU Xiaoli，CAI Tiancong，ZHANG Wensheng DOI: 10.13228/j.boyuan.issn1006-6543.20210043 Zinc oxide was prepared by hydrothermal method with zinc nitrate as zinc source and ammonia, sodium hydroxide and sodium carbonate as precipitant. The crystal growth of the precursors obtained from different precipitants and their hydrothermal products were studied.The products were characterized by X-ray diffraction and transmission electron microscopy. The results show that basic zinc carbonate can be obtained from the precursor formed with sodium carbonate as precipitant by hydrothermal method, while zinc oxide can be obtained from the precursor formed with ammonia and sodium hydroxide as precipitants by hydrothermal method. The growth laws of zinc oxide crystals prepared with ammonia and sodium hydroxide as precipitants conform to different linear growth relationships. Their crystals have different product morphologies. 2023 Vol. 33 (01): 94-98 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 99 Research progress in high temperature solid self-lubricating composite materials Hot! LI Yanmin，LIU Xuequan，LI Jinpu，SHI Yulei，JIANG Lijuan DOI: 10.13228/j.boyuan.issn1006-6543.20220032 With the rapid development of science and technology,the demand for high temperature solid self-lubricating composite materials in aerospace,metal forming,electric power and other industrial fields is increasing year by year.High temperature solid self-lubricating composite materials have become a research hotspot in the field of lubrication. In this paper, the research status of high temperature solid lubricants,high temperature solid self-lubricanting composite materials and its preparation technology in recent years were mainly reviewed, and the design concepts for new high temperature solid self-lubricating composite materials were summarized. 2023 Vol. 33 (01): 99-106 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 107 The control of internal defects during laser melting deposition by external physical field Hot! HUANG Xina，CAO Yubo，YUE Wen，ZHAI Yuewen，YANG Hao，WANG Chengbiao DOI: 10.13228/j.boyuan.issn1006-6543.20220020 Laser melting deposition technology is an advanced manufacturing technology based on the principle of layering-superposition. The metal powders sent synchronously are melted layer by layer and rapidly solidified according to the designed route, under the action of high-energy laser heat source. It has the advantages of high forming accuracy, good machining flexibility, uniform internal structure, excellent mechanical properties and suitable for the preparation of metal that difficult to machine. In consequence, it has a broad application prospect in aerospace and other fields. However, the large-scale application is limited by the defects such as lack of fusion, microcrack and pore, which are easily generated in the process of laser melting deposition. The microstructure of the laser melting deposited component shows obvious anisotropy and large residual stress exists because of the rapid heating and cooling during the deposition process, resulting in deformation and cracking. Many researchers have studied how to eliminate the internal defects of laser melting deposited components. In this paper, the methods of applying temperature field, ultrasonic field, electromagnetic field and compound field during the forming process to improve the internal structure and properties of laser melting deposited components are reviewed which may provide guidance for improving the comprehensive properties of laser melting deposited components. 2023 Vol. 33 (01): 107-114 [Abstract] ( 5 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 115 Review on preparation of CoCrFeNi-X high entropy alloy by selective laser melting Hot! HOU Qingling，GE Yaqiong，CHANG Zexin，MAMingfeng，LI Jipeng DOI: 10.13228/j.boyuan.issn1006-6543.20220029 CoCrFeNi high entropy alloy has become one of the most popular systems in the pursuit of high toughness parts research because of its excellent plastic deformation ability and high yield strength of a single stable facecentric cubic solid-solute structure. At the same time, selective laser melting technology has unparalleled advantages over traditional preparation methods due to its flexible forming size and ultra-fast heating and cooling rates. In this paper, the CoCrFeNi-X high-entropy alloy systems successfully created by the selective laser melting technology in recent years and the effects of tissue structure on mechanical properties for eight different alloy systems in terms of phase structure and tissue morphology were analyzed；the effects of the preparation process on forming density and mechanical properties for three CoCrFeNi-X high entropy alloys formed parts were examined；Finally, a detailed analysis of the current status of the two mainstream alloy systems, CoCrFeNi-Alx and CoCrFeNi-Mn, was done on the alloy composition design. The research and analysis are expected to provide some theoretical guidance for the experimental research and industrial application of preparing CoCrFeNi-X system high entropy alloys by selective laser melting technology. 2023 Vol. 33 (01): 115-119 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 120 A method for determining nitrogen in Ti (C, N) powder with high nitrogen content by inert gas melting thermal conductivity method Hot! HE Mingqian，ZHONG Hua DOI: 10.13228/j.boyuan.issn1006-6543.20220004 Since traditional methods can only measure Ti (C, N) with a nitrogen content of less than 5%, it cannot be applied to Ti (C, N) with a high nitrogen content. Therefore, a method for determining the nitrogen content of high nitrogen content Ti (C, N) powder by inert gas melt-thermal conductivity method was established, which could effectively solve the shortcomings of traditional methods, and the upper limit of detection could be increased to 14%. Using an ONH analyzer, the experimental conditions were finally optimized to 0.1 g of the sample mixed with 0.65 g of nickel and 0.16 g of tin, and then placed into a high-temperature graphite crucible. Carrier gas transports nitrogen released in the molten state to a thermal conduction tank for determination. In this paper, the“segmented heating”method was used, the analysis power was gradually increased from 1.5 kW to 3.8 kW. Compared with direct heating, the“segmented heating”method can effectively increase the release rate and stability of nitrogen. Under the above conditions, the relative standard deviation of the Ti (C, N) determination results with high nitrogen content is 0.3%, and the analysis results are consistent with the results of distillation titration. Therefore, the accuracy and stability of the method can fully meet the needs of the determination of 5% to 14% high nitrogen content Ti (C, N). 2023 Vol. 33 (01): 120-124 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 5 )

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