Papers by Keyword: Tungsten Carbide

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Authors: Anton Gnidenko
Abstract: Quantum-mechanical calculations were performed for investigation of tensile strength for WC/Co/WC systems with the thickness of the cobalt interlayer of 3 and 7 atomic layers. It has been shown that the cobalt interlayer increasing leads to decreasing of the tensile strength from 17 GPa to 14 GPa. In addition, vacancy-type defect formation reduces the tensile strength of about 2 times.
Authors: W.K. Chen, Tsunemoto Kuriyagawa, H. Huang, Haruhiko Ono, Masaru Saeki, Katsuo Syoji
Authors: Han Huang, Rudy Irwan, Tsunemoto Kuriyagawa
Abstract: Nanoindentation was used to study the deformation and removal mechanisms of cemented tungsten carbide. It was found that the microstructure of the material has significant influences on its mechanical properties, which determines the critical conditions for damage-free nanogrinding. The results also indicated that when material removal events occur at nanometric scale, such influences should be taken into account for gaining the full potential of nanogrinding.
Authors: Pei Lum Tso, Chao Chun Tseng
Abstract: In order to cope with high demanded industry requirements. The super-hard alloys such as Tungsten Carbide have been widely used in aerospace and defense industries. So far, the grinding operation is still the most popular machining process being used to cut these materials in shape. But, owing to the nature of these materials mechanical properties, always made it very difficult to grind as well as to cut. Nevertheless, the allowable grinding parameters are resisted to very limited range and always require use very expensive super abrasive grinding wheel. Recently, study by many researchers show that the ultrasonic assist grinding had the advantage of higher material removal rate, less cutting force and lower cutting temperature. In the mean time, the tool life had been improved greatly. In this study, the conventional GC grinding wheel was used in the experiments to study the material removal rate; grinding force; surface roughness as well as specific grinding energy with and without the ultrasonic assist. The results show that these difficult-to-cut materials can be ground easier with proper ultrasonic assist and low-priced grinding wheel.
Authors: Feng Jiao, Ying Niu, Jia Liang Qi, Jie Li
Abstract: The prediction of tool wear can help understand the influence of tool wear on the machining process and result, and change or grind the worn tool in time. The two-dimensional ultrasonic vibration turning method can reduce the crack of tool and decrease the negative effect on processing thus extends the tool life. In this paper, two-dimensional ultrasonic cutting theory was applied to the precision machining of tungsten carbide. With self-developed two-dimensional ultrasonic cutting device, series of cutting experiments were carried out. During cutting process, the flank wear under different cutting length was observed; flank wear situations were compared with those in traditional cutting. In order to predict the tool wear and thus heighten the machining precision, a tool wear prediction model based on time series analysis method was built in the paper. The research results show the built AR (9) time series model can predict the flank wear condition with high precision.
Authors: H. Norafifah, M.Y. Noordin, S. Izman, D. Kurniawan
Abstract: Chemical vapor deposition (CVD) diamond coatings are being developed to be applied on carbide cutting tools to enhance wear resistance and increase tool life. As a prerequisite, for ensuring adhesion of CVD diamond on tungsten carbide substrate, it is necessary to prepare high surface roughness and to remove the cobalt on tungsten carbide surface during the pretreatment. In this study, a two step acid pretreatment was examined for those purposes. Etching using modified Murakamis reagent was initially performed to roughen the surface. Subsequently, the carbide was immersed in nitric acid to remove cobalt. Concentration of the acid solutions and reaction time were varied. Results showed that the initial step by modified Murakamis reagent etching resulted in a surface roughness of Ry = 6.95 µm, which is a 15% increase from the average initial surface roughness. The second step by nitric acid immersion on modified Murakamis reagent etched carbide samples resulted in carbide surfaces with zero cobalt content, confirming the effectiveness of the pretreatment.
Authors: Mohd Yusof Noordin, A.S. Noor Adila, S. Izman, D. Kurniawan
Abstract: Pretreatment on tungsten carbide (WC-Co) surface is critical for obtaining perfectly adherent diamond coatings by chemical vapor deposition (CVD). The carbide surface should have high roughness to facilitate diamond nucleation and adhesion. The presence of cobalt—common binder for tungsten carbide—on the surface to be coated should be made minimum since it has negative influence on the diamond deposition process. In this study, surface pretreatment on tungsten carbide using sulfuric acid was evaluated in terms of the resulted cobalt removal and the surface roughening. The variables included were acid concentration, reaction temperature, and reaction time. The resulted surface roughness was 29% higher than initial, averaged at 1.07 µm. The acid pretreatment was also found effective in eliminating surface cobalt.
Authors: Hong Lin Li, Li Gou, Jun Guo Ran
Abstract: Diamond film was synthesized on Co-deficient (Co content is about 0.5%) WC-Co substrate using microwave plasma chemical vapor deposition (MPCVD) equipment without special pretreatment. SEM, XRD, Rockwell-indentation test and scratch test were used to analyze the structure and morphology of the diamond film and its adhesion to the substrate. Co content was also measured by EDAX. The results show that the film synthesized is of ideal diamond structure with perfect and uniform grains, dense and continuous surface and strong adhesion. Co content on the surface of the substrate is about 0.8% after 20h deposition, which is considered as one of the main causes to get good adhesion.
Authors: Engku Mohammad Nazim, Sudin Izman, Ali Ourdjini, T. Abubakar, H. Mas-Ayu
Abstract: The effect of seeding using different mixtures of diamond and silicon carbide (SiC) powders on the adhesion strength of hot-filament chemical vapor deposition (HFCVD) diamond coating on WC-6% Co substrates was studied. Diamond powders with the average grain size of 0.5 μm mixed with various concentrations of SiC powder of 175μm average grain size were employed. Diamond layers were deposited using a production unit of HFCVD technique. The diamond film morphology and the diamond quality were examined using field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and Raman spectrometer respectively. It was found that the diamond morphologies produced and the qualities were almost the same for all the seeding mixtures of pretreatment. With the blasting technique employed to determine the adhesion strength it was found that the highest diamond film adhesion strength was achieved from the seeding of a mixture of diamond with 5g/l SiC powder.
Authors: Adrian Catalin Pavalache, Gabriel Marius Dumitru, Elena Manuela Stanciu, Raúl López, Mihai Vasile, Dan Petre
Abstract: The use of laser cladding (LC) technology for the improvement of surface properties in various mechanical design applications has given rise to the development of application-oriented composites. The present paper furnishes relevant notes on an experimental approach to the design optimization of experiments regarding WC-Co based layers obtained by laser cladding. The current paper emphasizes the influence of parameter variation on the characteristics of the deposited layer and reports the manner in which the heat input and the laser power density influence the microstructure.
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