Study On The Influence Of Using Condition Matter To Coatings’ Property And Design

PVD coating can greatly improve the surface properties of materials, for its specialproperties such as high hardness, wear-resisting antifriction, high oxidation temperature,corrosion resisting. Work pieces and parts after depositing coating always contacted with thesurrounding environmental media when used. Study about the effect of environment on theusing performance of coating and the failure form of coating in the using environment canprovide the theoretical basis and directions when we design coating.In this paper, closed field unbalanced magnetron sputtering ion plating technology wereused to deposit TiAlN single coating, and Ti/TiAlN multilayer composite coatings on H13steel substrate. Optical microscope and Hitachi S-4800field emission scanning electronmicroscopy (SEM) and EDS were used to observe the failure morphology of coating insurface and cross-section. Samples were heated in molten aluminum to simulate the actualproduction situation of aluminum die-casting mold to study thermal fatigue characteristicsand thermal fatigue failure mechanism. Samples’ morphology of the section and surface afterin molten aluminum for a long time were observed to study coatings’ failure mechanism.Films in different series were deposited in surface of W6Mo5Cr4V2high speed steel substrateto study the friction and wear properties between films and aluminum alloys. And films’wearfailure mechanism between film and aluminum alloy also were discussed. The mainconclusions could be divided to three points:1. Molten aluminum could do a serious corrosion effect to H13steel. Depositing TiAlN coating or Ti/TiAlN multilayer film on the surface of H13could prevent corrosion in a certainextent and the Ti/TiAlN multilayer film was better. The surface of the sample with Ti/TiAlNmultilayer film could keep smooth because of the intact Ti/TiAlN multilayer film has a goodperformance of inoxidizability. Excepting alternating stress, aluminum liquid corrosion andhigh-temperature oxidation were the crucial characteristic of coatings thermal fatigue inmolten aluminum.2. Results indicated that the reaction between substrate and molten aluminum was the keyfactor to cause delaminating of TiAlN coating. The molten aluminum intruded into theinterface between substrate and film through the border or defects in coatings. The failureprocess could be divided into three categories listed as the stage of molten aluminum’sinvasion, molten aluminum’s corrosion and the delaminating of coating.3. The coefficient between each coating（TiN，TiAlN，CrN，CrMoN，W:a-C）and aluminumalloy range from0.3to0.6. The W:a-C coating can effectively decrease coefficient and avoidagglutination when wearing with aluminum alloy because of his self-lubricating. The gross ofagglutination on W:a-C coating was4.6%of agglutination on6542HSS. Aluminum alloycould easily adhere on the coating because of the effect of welding and it could result incoating’s exfoliation. Agglutination came up with a higher demand in coating-substrateadhesion.