Zhang S.-Q.,Xiamen Golden Egret Special Alloy Co.
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy
WC-10Co-0.6Cr3C2 cemented carbides was prepared by sinter-HIP. The physical and mechanical properties of the alloys with different carbon contents were tested by OM RHA analysis, magnetic saturation and coercive force analysis. The results show that the hardness, density and coercive force of the alloys decrease with carbon content increase. When the carbon content of the alloy varies from 5.41% to 5.55%, the alloys have a two-phase structure. When the carbon content of the alloys is lower than 5.41%, a carbon deficiency phase, i.e. the θ phase appeares. When the carbon content of the alloys is higher than 5.55%, a free carbon phase appeares. Source
Lai J.,Xiamen Golden Egret Special Alloy Co.
Solid State Phenomena
Titanium alloys are difficult-to-cut materials, and the rapid wear of cutter is a big problem for machining of these alloys. In this paper, the wear characteristics of seven milling cutters in milling of TC4 (Ti6Al4V) titanium alloys are investigated. The results indicated that the averaged flank wear of each cutter linearly increases as the accumulated cutting length expands. Large radial rake angle as well as axial rake angle is favor for reducing cutter wear .© (2011) Trans Tech Publications, Switzerland. Source
Zhang S.,Xiamen Golden Egret Special Alloy Co.
Fenmo Yejin Jishu/Powder Metallurgy Technology
A gradient sintered WC-Ti(C, N)-(Ti, W)C-(Ta, Nb)C-Co cemented carbide with three different carbon contents was fabricated by one-step sintering procedure. The microstructure and element distribution of the cemented carbides were investigated by SEM and EPMA. Vickers hardness (HV30) and fracture toughness (KIC) were measured. The aim of this work is to relate the variation in carbon content to the resulting microstructures and to the mechanical behavior of these alloys. The results show that all alloys create a surface zone depleted of cubic carbides containing Ta, Ti, Nb, and ductile binder phase rich Co. The zone width and WC grain size increase with increasing carbon content. Hardness decrease and fracture toughness increase with increasing carbon content. ©, 2015, Beijing Research Institute of Powder Metallurgy. All right reserved. Source
Wu C.,Xiamen Tungsten Co. |
Wu C.,Xiamen Golden Egret Special Alloy Co.
International Journal of Refractory Metals and Hard Materials
Ultrafine tungsten powders with a grain size below 0.5 μm are key raw materials for fabricating ultrafine cemented carbides. Conventional hydrogen reduction technique has been utilized to prepare the ultrafine tungsten powders. In the present work, highly pure nano-needles of violet tungsten oxide (WO 2.72) were reduced by dry hydrogen. Nucleation and growth of the metallic tungsten in the early stage of hydrogen reduction have been studied by XRD, FESEM and HRTEM. Mechanism of formation of nano-size tungsten powders is proposed and a concept of in-situ hydrogen of the nano-needle WO 2.72 is presented. Empirical relations between an average diameter of nano-needle WO 2.72 and an average particle size of the resultant tungsten powders in both stage of nucleation and industrial conduction have been established. These empirical relations could be a reasonable guidance for suitably choosing the raw materials of nano-needle WO 2.72 to prepare ultrafine tungsten powders. It has been determined that the BET special surface areas of the in-situ hydrogen-reduced tungsten powders with the average particle size of 0.2 μm and 0.3 μm, which were produced from the raw nano-needle WO 2.72 powders with the average diameter of 60 nm and 80 nm, are 6.03 m 2/g and 4.65 m 2/g, and the oxygen contents are 0.35% and 0.29%, respectively. © 2011 Elsevier Ltd. All rights reserved. Source
Zou L.,Xiamen Golden Egret Special Alloy Co.
Fenmo Yejin Jishu/Powder Metallurgy Technology
A gradient sintered WC-Ti(C,N)-NbC-Co cemented carbides were fabricated with two different Ti(C,N) contents (0.5% and 1.5%) and by one-step sintering procedure, and were coated with the TiN/MT-TiCN/Al2O3 coating using chemical vapor deposition (CVD). The effects of the variation in Ti(C,N) content on the resulting microstructures and the mechanical behavior of gradient cemented carbide and its cutting performance of coated inserts in turning of 45# steel were studied. The results show that both the alloys create a surface zone depleted of cubic carbides, with the increase of Ti(C,N) content, the zone width increases from 11μm to 35μm and the average WC grain size decreases from 1.97 μm to 1.60 μm; meanwhile, hardness (HV30) and coercive force (Hc) increase, while fracture toughness (KIC) and density decrease. The cutting tests demonstrate that the coated gradient inserts with a higher Ti(C,N) content have a slightly decreased wear resistance, but obviously improve impact resistance. ©, 2015, Beijing Research Institute of Powder Metallurgy. All right reserved. Source