Entity

Time filter

Source Type


Min X.,Hunan Research Institute of Metallurgy and Materials | Wang Y.,Central South University | Xia G.,Hunan Research Institute of Metallurgy and Materials | Yan S.,Hunan Research Institute of Metallurgy and Materials | Lu J.,Hunan Research Institute of Metallurgy and Materials
Fenmo Yejin Jishu/Powder Metallurgy Technology | Year: 2010

The high energy spray forming technology and its applications to heat-resistant materials were introduced. Vacuum hot pressing and high-pressure hot isostatic pressing were used to improve densification. The results show that the relative density of pure tungsten throat liner fabricated by plasma spray forming is 85.6%, that by vacuum hot pressing is increased to 91.7%, and that by high-pressure hot isostatic pressing is to 96.7%, which indicates that high-pressure hot isostatic pressing can raise density. High energy spray forming technology can also fabricate heat-resistant materials with complicated shape, such as special-shaped parts like W/Mo composite nozzle tube, tungsten crucible, tungsten heating unit, heterotypical component of highexplosive antitank HEAT and MoSi2 gyroroter etc.


Chu Z.-Q.,Central South University | Chu Z.-Q.,Hunan Research Institute of Metallurgy and Materials | Guo X.-Y.,Central South University | Zhang L.,The State Key Laboratory of Powder Metallurgy | Liu D.-H.,Hunan Research Institute of Metallurgy and Materials
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy | Year: 2015

The prealloy powders used in diamond matrix were produced by super high pressure water atomization technology. The diameter and micrograph of prealloy powders were measured by laser scattering particle analyzer and scanning electron microscope. The effects of atomizing pressure, alloy melt superheat and diameter of delivery on the average diameter and micrograph of prealloy powders were studied. The results show that, with increasing atomization pressure, alloy melt superheat and decreasing diameter of delivery, the average diameter of the powder decreases, and the micrograph of prealloy powders changes from spherical to similar spherical and then to irregular shape. When the atomization water pressure is over 60 MPa and the alloy melt superheat is above 250 ℃, increasing water pressure and alloy melt superheat has no obvious effect on the powders diameter. The delivery will be frequently stopped when the diameter of delivery is less than 2.0 mm. © 2015, Central South University. All right reserved.


Liu Q.-N.,Central South University | Liu Y.,Central South University | Li F.,Central South University | Min X.-B.,Hunan Research Institute of Metallurgy and Materials
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy | Year: 2012

Iron-based amorphous alloy coatings were synthesized on Q235 stainless steel surface by detonation gun thermal spraying. Post heat treatment was conducted in the atmospheric environment within the temperature ranged from 500°C to 700°C. The effect of heat treatment on phase structure and wear characteristics of the coating was investigated. The results show that, with increasing heat treatment temperature, the content of amorphous phase has a obvious decrease, changing from 85.2% to 38.94% after 700°C heat treatment; Iron-based amorphous alloy coatings show more dense structure after heat treatment. The average microhardness of sprayed coating before heat treatment is 1095.6 HV0.05, and it has little change after 500°C heat treatment, the microhardness increases slowly with increasing heat treatment temperature; compared with sprayed coating condition, the friction coefficients of coating increase slightly after heat treatment at 500°C and 600°C; the friction coefficient decreases by 15% after heat treatment at 700°C; the wear resistance decreases by 20% after heat treatment at 600°C, and the best wear resistance property is obtained at this time; while the mass wear loss is 3 times of that of the sprayed coating after heat treatment at 700°C, which is because of the decreasing of amorphous phase and oxide in the coating resulting in coating embrittlement. The wear behaviour is changing from adhesive wear to abrasive wear, then to the mixture of the two wear mechanisms.


Chu Z.-Q.,Central South University | Chu Z.-Q.,Hunan Research Institute of Metallurgy and Materials | Guo X.-Y.,Central South University | Tian Q.-H.,Central South University | Zhang L.,Central South University
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy | Year: 2015

Vanadium nitride was prepared by carbon thermal reduction method using V2O5 as raw material. The morphology and composition of the reduction products were observed and analyzed by SEM and XRD. The contents of carbon, nitrogen and oxygen of the product were tested, and the effects of raw materials parameters, such as carbon content, temperature and time on the reduction of the product were also studied. The results show that the reduction product is a solid solution of carbon and nitride. The carbon content of raw material is the key factor to affect the content of nitrogen in the reaction products, and nitrogen content in the product has the highest value of 14.76% when the mass fraction of carbon in raw materials is about 21%; the nitriding temperature should be controlled in the range of 1400~1420 ℃, and the nitriding time can be reached by 4 h. © 2015, Central South University. All right reserved.


Wang Y.,Central South University | Xiong X.,Central South University | Xie L.,Central South University | Xu X.,Central South University | And 2 more authors.
Materials Transactions | Year: 2011

Refractory metallic thin-walled products of 95W-3.5Ni-l.5Fe (in mass%) were fabricated by plasma spray forming (PSF) in argon atmosphere at 1.01 × 105 Pa followed by high temperature sintering (1200, 1300, 1400 and 1465°C). Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Archimedes method, differential scanning calorimetry (DSC) and X-ray diffractometer (XRD) have been employed to study microstructure, solubilities, density, solidus and liquidus temperatures and phases of the parts. Lamellar structure consisting of vertical columnar grains and fine particles was found in PSF deposits. Supersaturated solid solutions were formed in the deposits with the relative density of 88 ± 2%. Solidus and liquidus temperatures of γ phase were measured to be 1392 and 1412 ± 5°C, respectively. Initial lamellar structure was remained in the tested samples after sintering at lower temperatures ( 1200°C/90 min, 1300°C/90 min and 1400°C/ 15,90 min) and turned into granular structure at 1465°C/5,15,30,90 min. In addition, the relative densities of deposits, after sintering at 1200, 1300,1400 and 1465°C for 90 min, were increased from 88 to 90,92,94 and 98 ± 2%, respectively. A five-stage sintering mechanism proposed by us previously has been re-validated and double checked by experimental results. ©2011 The Japan Institute of Metals.

Discover hidden collaborations