Sduty On The Low-temperature Deposition And Mechanical Properties Of ?-?Al,Cr?₂O₃ Films Preparated By High Power Pulsed Magnetron Sputtering

The rapid development of modern processing industry to high speed,automation and precision requires that the cutting tools have excellent high temperature hardness and toughness at the same time,and they are not bonded,diffused and oxidized with the processed materials at high temperature.The tools with?-Al₂O₃ coating meet these requirements.However,the impacted of exhaust emission on environment and too high deposition temperature for traditional preparation of?-Al₂O₃ film by chemical vapor deposition have greatly restricted the practical application.In this paper,?-?Al,Cr?₂O₃ thin films were successfully deposited on Si?001?substrates at the low-temperature of 540?with high power pulsed magnetron sputtering?HPPMS?system by sputtering AlCr targets with different atomic ratios in Ar+O₂ mixture atmosphere.The phase structures,morphologies,compositions of the as-deposition films were characterized by Grazing Incidence X Ray Diffraction?GIXRD?,Scanning Electron Microscope?SEM?and Energy Dispersive Spectrum?EDS?and the mechanical properties of the films were evaluated by Hysitron TI 950nano-indentation tester,respectively.The main results are as follows.The deposition parameters of the films with Al₅₀Cr₅₀ target were studied,the results indicate that thin films with dense,flat,uniform 20 nm grains were grown.Mixture phases of amorphous,?-Cr₂O₃ and little?-Al₂O₃ were deposited at 500?and 520?.However,films with?-?Al,Cr?₂O₃ main crystsal phase,without metastable phase,can be prepared at 540?,10%oxygen partial pressure and 0.5 Pa working pressure.Then the results of sputtering Al_XCr_100-X?x=0/50/70/80/90/100?alloy targets show that target poisoning was serious when the percentage of Cr atoms was less than 20%,on the contrary,the sputtering process was pretty stable without the occurrence of aces when the percentage of Cr atoms was more than 30%.At the condition of 540?,10%oxygen partial pressure and 0.5 Pa working pressure,the chemical compositions of all thin films are?Al,Cr?₂O₃.The films deposited by sputtering Al₅₀Cr₅₀ and Al₇₀Cr₃₀ targets contain?-?Al,Cr?₂O₃ main crystal phase and?-Cr₂O₃,without metastable Al₂O₃,but the crystallinity of the films corresponding to the Al₇₀Cr₃₀ target is better.However,the films deposited with Al₈₀Cr₂₀ and Al₉₀Cr₁₀ targets contain?-Cr₂O₃ main crystal phase,also the metastable?-Al₂O₃ appears at the same time.The films with serious spark discharge deposited by sputtering Al target contain?-Al₂O₃main crystal phase and little?-Al₂O₃.On the contrary,the?-Cr₂O₃ films with pretty stable sputtering process deposited by sputtering Cr target were made up of grains ranging from 100to 200 nm.Boeh films present good binding force with Si?001?substrates.With the decrease of the percentage of Cr atoms in the sputtering targets,the hardness of the films increases first and then decreases.The hardness of?-?Al,Cr?₂O₃ films deposited with Al₇₀Cr₃₀ target is the highest,namely 30.3 GPa...