Gear Surface Composite Plating Ti < Sub > 1 - X < / Sub >, < Sub > X < / Sub > N Film Technology And Performance Study

Gears, which are widely used in transmission, occupy an important position in themechanism Industries. The performance of the gear material is closely related to the use ofthe service condition andstatus and working life of machines. There are many methods ofstrengthen surface properties of gears now, such as nitriding, carburizing, spray painting,vapor phase deposition, etc. As the demand of better gear performance, composite surfacetreatment of heat treatment and vapor deposition instead of single surface treatment is a newtrend of improving gear performance. With PVD （physical vapor deposition）, there aremany studies on TiAlN coatings. On the contrary, there are little studies on the effects ofAl content on coating structure and mechanical property. In this paper, the effects ofcomposite surface treatment and different Al content on the properties of gear materialswere discussed.With composite treatment of ionitriding and multi-arc ion technology, single andgradient Ti-Al-N coatings with different Al content were plated on40Cr surface in conditionof pure Ti target and the target with ratio of Ti and Al1:1,1:2,1:3respectively, and themanufacture process of Ti_0.33Al_0.67N was optimized. The surface topography, the phasestructure, the micro-hardness, the adhesion strength, the high-temperature oxidation andwear-resistant were tested by metallographic microscope, scanning electron microscope,micro-hardness tester, scratch tester. The results showed that:1. With ionitriding, thick nitriding Layer which improved rational gradient hardnessbetween gear and coating and higher adhesion strength between the coating and substratewas plated on gear surface.2. With change of pushed bias voltage, target current and N2pressure, the morphologyof the coatings were changed. The pushed bias voltage had a great influence in performanceon adhesion strength of coating which had a maximum value when pushed bias voltageincreased. The target current affected coating micro-hardness which got a best value withincreased current in a certain scope. The Ti_0.33Al_0.67N coating had2.2-2.8μm thickness,2634HV_0.1micro-hardness and44N adhesion strength when the process was pushed biasvoltage150V, target current of TiAl alloy60A and N₂pressure0.5Pa.3. The structures of Ti_1-xAl_xN single coating and gradient coating were bothface-centred cubic structure, and main phases were TiAlN phase. Maximum diffractionmoved right and lattice constant reduced when Al content increased. 4. The gradient coating of Ti_1-xAl_xN ensured coating micro-hardness and increasedadhesion strength between the coating and substrate.5. The gradient coating of Ti_1-xAl_xN had better anti-oxidation than40Cr substrate andTiN coating, such as Ti_0.33Al_0.67N had an unbroken coating at800℃when40Cr substrateoxidized obviously at300℃and TiN coating oxidized at500℃.6. At a same test condition, frictional factor and abrasion loss of Ti_1-xAl_xN gradientcoating were lower than40Cr substrate and TiN coating, when TiN/TiAlN coating werelower than40Cr substrate.