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1、外文文献翻译 例如：下面是一个样板，如需要更多的机械相关专业的外文文献可以联系QQ: 763077177(非诚勿扰)Coating thickness effects on diamond coated cutting toolsF. Qin, Y.K. Chou,D. Nolen and R.G. ThompsonAvailable online 12 June 2009.Abstract：Chemical vapor deposition (CVD)-grown diamond films have found applications as ahard coating for cutti

2、ng tools. Even though the use of conventional diamond coatings seemsto be accepted in the cutting tool industry, selections of proper coating thickness for differentmachining operations have not been often studied. Coating thickness affects thecharacteristics of diamond coated cutting tools in diffe

3、rent perspectives that may mutuallyimpact the tool performance in machining in a complex way.In this study, coating thickness effects on the deposition residual stresses, particularlyaround a cutting edge, and on coating failure modes were numerically investigated. Ontheother hand, coating thickness

4、 effects on tool surface smoothness and cutting edge radii wereexperimentally investigated. In addition, machining Al matrix composites using diamondcoated tools with varied coating thicknesses was conducted to evaluate the effects on cuttingforces, part surface finish and tool wear.The results are

5、summarized as follows. Increasing coating thickness will increase theresidual stresses at the coatingsubstrate interface. On the other hand, increasing coatingthickness will generally increase the resistance of coating cracking and delamination. Thickercoatings will result in larger edge radii; howe

6、ver, the extent of the effect on cutting forces alsodepends upon the machining condition. For the thickness range tested, the life of diamondcoated tools increases with the coating thickness because of delay of delaminations.Keywords: Coating thickness; Diamond coating; Finite element; Machining; To

7、ol wear1. IntroductionDiamond coatings produced by chemical vapor deposition (CVD) technologies havebeen increasingly explored for cutting tool applications. Diamond coated tools have greatpotential in various machining applications and an advantage in fabrications of cutting toolswith complex geome

8、try such as drills. Increased usages of lightweight high-strengthcomponents have also resulted in significant interests in diamond coating tools. Hot-filamentCVD is one of common processes of diamond coatings and diamond films as thick as 50 mhave been deposited on various materials including cobalt

9、-cemented tungsten carbide(WC-Co) . There have also been different CVD technologies, e.g., microwave plasma assistedCVD , developed to enhance the deposition process as well as the film quality too. However,despite the superior tribological and mechanical properties, the practical applications ofdia

10、mond coated tools are still limited.Coating thickness is one of the most important attributes to the coating systemperformance. Coating thickness effects on tribological performance have been widely studied.In general, thicker coatings exhibited better scratch/wear resistance performance than thinne

11、rones due to their better load-carrying capacity. However, there are also reports that claimotherwise and . For example, Dorner et al. discovered, that the thickness ofdiamond-like-coating (DLC), in a range of 0.73.5 m, does not influence the wear resistanceof the DLCTi6Al4V . For cutting tool appli

12、cations, however, coating thickness may have amore complicated role since its effects may be augmented around the cutting edge. Coatingthickness effects on diamond coated tools are not frequently reported. Kanda et al. conductedcutting tests using diamond-coated tooling . The author claimed that the

13、 increased filmthickness is generally favorable to tool life. However, thicker films will result in the decreasein the transverse rupture strength that greatly impacts the performance in high speed orinterrupted machining. In addition, higher cutting forces were observed for the tools withincreased

14、diamond coating thickness due to the increased cutting edge radius. Quadrini et al.studied diamond coated small mills for dental applications . The authors tested differentcoating thickness and noted that thick coatings induce high cutting forces due to increasedcoating surface roughness and enlarge

15、d edge rounding. Such effects may contribute to the toolfailure in milling ceramic materials. The authors further indicated tools with thin coatingsresults in optimal cutting of polymer matrix composite . Further, Torres et al. studied diamondcoated micro-endmills with two levels of coating thicknes

16、s . The authors also indicated thatthe thinner coating can further reduce cutting forces which are attributed to the decrease in thefrictional force and adhesion.Coating thickness effects of different coating-material tools have also been studied. For singlelayer systems, an optimal coating thicknes

17、s may exist for machining performance. Forexample, Tuffy et al. reported that an optimal coating thickness of TiN by PVD technologyexists for specific machining conditions . Based on testing results, for a range from 1.75 to7.5 m TiN coating, thickness of 3.5 m exhibit the best turning performance.

18、In a separatestudy, Malik et al. also suggested that there is an optimal thickness of TiN coating on HSScutting tools when machining free cutting steels . However, for multilayer coating systems, nosuch an optimum coating thickness exists for machining performance .The objective of this study was to

19、 experimentally investigate coating thickness effects ofdiamond coated tools on machining performance tool wear and cutting forces. Diamondcoated tools were fabricated, by microwave plasma assisted CVD, with different coatingthicknesses. The diamond coated tools were examined in morphology and edge

20、radii bywhite-light interferometry. The diamond coated tools were then evaluated by machiningaluminum matrix composite in dry. In addition, deposition thermal residual stresses andcritical load for coating failures that affect the performance of diamond coated tools wereanalytically examined.The sub

21、strates used for diamond coating experiments, square-shaped inserts (SPG422),were fine-grain WC with 6 wt.% cobalt. The edge radius and surface textures of cuttinginserts prior to coating was measured by a white-light interferometer, NT1100 from VeecoMetrology.Prior to the deposition, chemical etchi

22、ng treatment was conducted on inserts to removethe surface cobalt and roughen substrate surface. Moreover, all tool inserts were ultrasonicallyvibrated in diamond/water slurry to increase the nucleation density. For the coating process,diamond films were deposited using a high-power microwave plasma

23、-assisted CVD process.A gas mixture of methane in hydrogen, 7501000 sccm with 4.47.3% of methane/hydrogenratio, was used as the feedstock gas. Nitrogen gas, 2.755.5 sccm, was inserted to obtainnanostructures by preventing columnar growth. The pressure was about 3055 Torr and thesubstrate temperature

24、 was about 685830 C. A forward power of 4.55.0 kW with a lowdeposition rate obtained a thin coating; a greater forward power of 8.08.5 kW with a highdeposition rate obtained thick coatings, two thicknesses by varying deposition time. Thecoated inserts were further inspected by the interferometer.A c

25、omputer numerical control lathe, Hardinge Cobra 42, was used to perform machiningexperiments, outer diameter turning, to evaluate the tool wear of diamond coated tools. Withthe tool holder used, the diamond coated cutting inserts formed a 0 rake angle, 11 reliefangle, and 75 lead angle. The workpiec

26、es were round bars made of A359/SiC-20p composite.The machining conditions used were 4 m/s cutting speed, 0.15 mm/rev feed, 1 mm depth ofcut and no coolant was applied. The selection of machining parameters was based uponprevious experiences. For each coating thickness, two tests were repeated. Duri

27、ng machiningtesting, the cutting inserts were periodically inspected by optical microscopy to measure theflank wear-land size. Worn tools after testing were also examined by scanning electronmicroscopy (SEM). In addition, cutting forces were monitored during machining using aKistler dynamometer.5. C

28、onclusionsIn this study, the coating thickness effects on diamond coated cutting tools werestudied from different perspectives. Deposition residual stresses in the tool due to thermalmismatch were investigated by FE simulations and coating thickness effects on the interfacestresses were quantified.

29、In addition, indentation simulations of a diamond coated WCsubstrate with the interface modeled by the cohesive zone were applied to analyze the coatingsystem failures. Moreover, diamond coated tools with different thicknesses were fabricatedand experimentally investigated on surface morphology, edg

30、e rounding, as well as tool wearand cutting forces in machining. The major results are summarized as follows.(1) Increase of coating thickness significantly increases the interface residual stresses, thoughlittle change in bulk surface stresses.(2) For thick coatings, the critical load for coating failure decreases with increasing coatingthickness. However, such a trend is opposite for thin coatings, for which radial cracking is thecoating failure mode. Moreover, thicker coatings have greater delamination resistance.(3) In addition, increasing the coating