Wang Z.,Beijing University of Technology |
Liu F.,Beijing University of Technology |
Liu F.,GRIPM Advanced Materials Co. |
He D.,Beijing University of Technology |
Tian L.,Beijing University of Technology
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2016
The Fe-Nb-C-B-Ni-WC (30%) iron-based tungsten carbide wear resistant hardfacing alloy was deposited on the Q235 byargontungsten-arcwelding (TIG) using flux-cored wire. The effect of niobium content on the dissolution of tungsten carbide in the alloy was studied by changing the niobium content from 1.0% to 3.8%. The results show that niobium content has a great influence on the degree of dissolution of tungsten carbide in the alloy. The primarily precipitated fine NbC particles around the tungsten carbide inhibit the dissolution of tungsten carbide. The amount of fine NbC determines the intensity of the inhibitory effect on the dissolution of tungsten carbide. The alloy with 2.5% niobium effectively inhibit the dissolution of tungsten carbide in the alloy, the original tungsten carbide particles were reserved more completely. © 2016, Harbin Research Institute of Welding. All right reserved.
General Research Institute for Nonferrous Metals, China, Beijing Hengyuan Tianqiao Power Metallurgy Co. and Gripm Advanced Materials Co. | Date: 2012-09-28
According to the invention, there are disclosed a power metallurgy composite cam sheet and a fabrication method thereof. The power metallurgy composite cam sheet is constructed by combining a power metallurgy cam be composited on a surface of a matrix. The fabrication method of the power metallurgy composite cam sheet includes sinter welding, braze welding, argon arc welding, laser welding, hot pressing and other methods. The powder metallurgy composite cam sheet fabricated by the invention has merits of stable size, good impact toughness, good abrasion resistance, low cost and so on, so that it can replace an integral cam sheet that is currently fabricated by forging, drawing, power metallurgy or other process. It is suitable for the case where a hollow camshaft is prepared by mechanical assembly, hydraulic forming, welding or other process, so that the usage requirements of an assembled camshaft can be met.
Yang Z.-L.,GRIPM Advanced Materials Co. |
Wang L.-G.,General Research Institute for Nonferrous Metals, China |
Wang L.-M.,GRIPM Advanced Materials Co. |
He X.-B.,University of Science and Technology Beijing |
And 3 more authors.
Rare Metals | Year: 2014
To inhibit the graphitization of diamond under high temperature and low pressure, diamond/SiC composites were firstly fabricated by a rapid gaseous Si vacuum reactive infiltration process. The microstructure and graphitization behavior of diamond in the composites under various infiltration temperatures and holding time were investigated. The thermal conductivity of the resultant materials was discussed. The results show that the diamond-to-graphite transition is effectively inhibited at temperature of as high as 1600 °C under vacuum, and the substantial graphitization starts at 1700 °C. The microstructure of those ungraphitized samples is uniform and fully densified. The inhibition mechanisms of graphitization include the isolation of the catalysts from diamond by a series of protective layers, high pressure stress applied on diamond by the reaction-bonded SiC, and the moderate gas-solid reaction. For the graphitized samples, the boundary between diamond and SiC is coarse and loose. The graphitization mechanism is considered to be an initial detachment of the bilayers from the diamond surfaces, and subsequently flattening to form graphite. The ungraphitized samples present higher thermal conductivity of about 410 W·m-1·K-1 due to the fine interfacial structure. For the graphitized samples, the thermal conductivity decreases significantly to 285 W·m-1·K-1 as a result of high interfacial thermal resistance. © 2014 The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg.
Liu Y.,Beijing Gang Yan Diamond Products Company |
Wang L.,GRIPM Advanced Materials Co. |
Wang L.,CompuTherm LLC |
Zhang C.,CompuTherm LLC
Advanced Materials Research | Year: 2013
Rare earth silicates (RE2SiO5 or RE2Si2O7; RE=Er, Lu, Y, Yb etc.) possess a low silica activity and good thermal stability, making them good candidates for EBC top coating materials. We have performed first-principles total energy calculations for the Er2O3-SiO2 pseudo binary system. The crystal lattice parameters and internal atomic coordinates of Er2SiO5 and Er2Si2O7 are optimized, and the electronic structure and formation enthalpies are calculated. The present study provides a theoretical basis for exploring practical applications of the materials. © (2013) Trans Tech Publications, Switzerland.
Yang Z.,University of Science and Technology Beijing |
Yang Z.,GRIPM Advanced Materials Co. |
He X.,University of Science and Technology Beijing |
Wang L.,GRIPM Advanced Materials Co. |
And 3 more authors.
Journal of the European Ceramic Society | Year: 2014
Diamond/SiC/(Si) composites were fabricated by Si vapor vacuum reactive infiltration. The coefficient of thermal expansion (CTE) of composites have been measured from 50 to 400. °C. With the diamond content increasing, CTE of composite decreased, simultaneously, the microstructure of the composites changed from core-shell particles embedded in the Si matrix to an interpenetrating network with the matrix. The CTEs of composites versus temperature matched well with those of Si. The Kerner model was modified according to the structural features of the composites, which exhibited more accurate predictions due to considering the core-shell structure of the composites. The thermal expansion behavior of the matrix was constrained by diamond/SiC network during heating. © 2013 Elsevier Ltd.