Papers by Keyword: Diamond Coating

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Authors: Shu Han, You Hong Gong, Ni Hong Yang, Sheng Chao Han
Abstract: Carbon Fiber Reinforced Plastic (CFRP) is widely used in aerospace field as an advanced composite material. Recently, more and more studies are focused on milling of CFRP with its increasing applications. In this paper, three different milling tools were chosen, and a systematic analysis on cutting force, surface quality and tool wear has been carried out to evaluate the tools. Experimental results indicate that the multi-flute tool with diamond coating has a better performance than the double spiral compression tool and the multi-tooth tool with AlTiN coating, with a lower cutting force, a better surface quality and a higher tool life than others, which would be a better tool for cutting of CFRP.
Authors: Fang Hong Sun, X.G. Wang, Zhi Ming Zhang, H.S. Shen, Ming Chen
Authors: José Vitor C. Souza, Maria do Carmo de Andrade Nono, João Paulo Barros Machado, Olivério Moreira Macedo Silva, F.C.L. Melo, M.V. Ribeiro
Abstract: Silicon nitride cutting tools have been used successfully for machining hard materials, like: cast irons, nickel based alloys, etc. However these cutting tools with diamond coating present little information on dry turning operations of gray cast iron. In the present work, Si3N4 square inserts was developed, characterized and subsequently coated with diamond for dry machining operations on gray cast iron. All experiments were conducted with replica. It was used a 1500, 3000, 4500 m cutting length, feed rate of 0.33 mm/rev and keeping the depth of cut constant and equal to 1 mm. The results show that wear in the tool tips of the Si3N4 inserts, in all cutting conditions, was caused by both mechanical and chemical processes. To understand the tool wear mechanisms, a morphological analysis of the inserts, after experiments, has been performed by SEM and optical microscopy. Diamond coated PVD inserts showed to be capable to reach large cutting lengths when machining gray cast iron.
Authors: Lin Zhang, Bin Yang, Wen Zhuang Lu, Guo Ping Ai
Abstract: The diamond coating can improve the performance and durability of cutting tool. To obtain the structure of nano/micro CVD diamond coating, the finite element analysis of nano/micro composite CVD diamond coating on boronized cemented carbide was carried on using ANSYS. The relationship between nanoand micron diamond layer thickness and coating fall off stress was simulated. The thickness of nanodiamond and the micron diamond layer was suggested for the nano/micro CVD diamond coating on boronized cemented carbide cutting tool.
Authors: Vladimir J. Trava-Airoldi, Evaldo Jose Corat, Vítor Baranauskas
Authors: Li Gou, Ji Lei Zhu, Jun Guo Ran, Suang Feng Yan
Abstract: In order to improve the adhesion between diamond coatings and cemented tungsten carbide (WC-Co) substrates, the diamond coatings were deposited on one kind of cobalt-deficient gradient WC-Co by the microwave plasma chemical vapor deposition (MPCVD). Scanning electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the diamond coatings. The results showed dense, well facet diamond coatings. The cobalt content at the surface of substrate was measured by electron probe microanalysis. It was found that Co did not largely move to the surface as usual with deposition time increasing compared with the conventional tungsten carbide; The cobalt content at the surface of substrate after deposition (about 1 wt %) was lower than before (3.42wt%), which improved diamond coating’s adhesion against the tungsten carbide substrate.
Authors: Zi Han Zhao, Liang Wen, Jin Bang Song, De Dong Yu, Ming Chen, Steve G.F. Shen
Abstract: Bone drilling commonly exists in clinical practice and the heat and force generated by the drilling process has a huge impact on the surgery effect and the recovery of patients. High speed drilling, proved to have less injury and be more efficient when compared to the traditional low speed drilling, is considered to be the development direction of bone drilling-related surgeries. In order to make a further study of the controlling of the heat and force during the bone drilling process, the experiment designed to examine the influence of the diamond coating has been conducted and the result indicates that the diamond coating generally has little influence on the drilling force, however, it can increase the drilling temperature to a certain extent which indicates that the diamond coating is not suitable to apply to bone drills under the conditions of the conducted experiments. The result of this research could be of some help to the development of new kinds of medical drills.
Authors: Sudin Izman, Mohammed Rafiq Abdul Kadir, Mahmood Anwar, Engku Mohammad Nazim, Low Yik Kuan, Eng Kean Khor
Abstract: Titanium alloys are commonly used in biomedical application in hard tissues replacement especially for knee and hip implants. Surface modifications are required prior to diamond coating process for improving the tribological and wear properties of the titanium alloy. In this study, experiments were carried out to investigate the effects of different pickling times as well as temperature on the adhesion strength of oxide layer formed on the Titanium alloy after oxidation process. The aqueous acid solution of HF and HNO3 was used as a pickling solution. The chemical pretreatment was carried out at 4 levels by varying the pickling time as well as temperature. All treated samples were thermally oxidized in a fixed parameters at 900 °C for 25 hours. Surface morphology, oxide layer thickness and adhesion strength were measured after each step using FESEM and Blast Wear Tester (BWT). It was revealed that the thickness of oxide layer increases with pickling time but the adhesion strengths become weaker. It was also found that the adhesion strength of oxide layer formed on Ti substrate surface increases with the increase of temperature while the thickness of the oxide layer decreased within 40oC pickling temperature.
Authors: Su Lin Chen, Bin Shen, Fang Hong Sun
Abstract: The present study reports the influence of graphene layers on the tribological performance of CVD diamond films when they are used as the solid lubricants. Friction tests are conducted on a ball-on-plate friction tester, where the stainless steel is used as the counterpart material. The CVD diamond film sample is a typical microcrystalline diamond (MCD) coating which is deposited on a flat tungsten carbide substrate using the hot filament chemical vapor deposition method (HFCVD). Besides the MCD sample, a polished MCD film (pMCD) and a polished tungsten carbide (pWC) are also adopted in frictional tests, aiming at illustrating the influence of the surface morphology, as well as the physical property, of the sample on the lubricative effect of graphene layers. The experimental results show that graphene layers can effectively reduce the coefficient of friction (COF), regardless of the samples. The MCD sample presents the lowest stable COF, which is 0.13, in dry sliding period when the graphene flakes are sparyed on the sliding interface; while the pMCD and pWC samples exhibit slightly higher COFs, which are 0.16 and 0.18, respectively. Comparatively, the COFs of these three samples obtained in dry sliding process without graphene are 0.20, 0.25 and 0.64. In additon, the MCD sample exhibits a much longer stable dry slidng process which is more than 5000 cycles. Comparatively, the other two tribo-pairs only exhibit a stable low-COF dry sliding period for around 2000 cycles. The reduction of COF could be attributed to the graphene flakes adhered on the sliding interface. It forms a layer of solid lubricative film with extremely low shear strength and significantly decreases the interactions between two contacted surfaces. The rugged surface of the MCD film provides sufficient clogging locations for graphene flakes, which allows the generated lubricative film enduring a long sliding duration. It can be arrived from this study that the tribological properties of the MCD film could be enhanced by simply adoping graphene layers as a solid lubricant. Furthermore, an improved performance of a variety of MCD coated cutting tools or mechanical components could be expected when they are utilized with graphene layers.
Authors: Qing Shun Tang, Yuan Hui Yang
Abstract: To improve the surface quality and adhesion of diamond film is the key factors to realize CVD diamond coating widely applied in the wear-resistance parts field. Through optimizing deposition process parameters, the article used the straight wiredrawing chemical vapor deposition to depose the diamond film in the bore surface of WC-CO carbide wiredrawing mould. The surface topography of the coating, film quality and surface roughness were detected and the preparation of CVD diamond film coated wire drawing mould in drawing copper wires production line was applied. The experimental results show that working life of diamond film coated wire drawing mould improved to 40~ 50 of that traditional hard alloy mould, and the controlled copper wire had the better precision and surface quality.
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