Traditionally, casting process and powder metallurgy methods are used to produce titanium aluminum alloy targets.
Loosen and shrink holes of Titanium-aluminum alloy target cannot be avoided by casting process. Large-size titanium-aluminum cast pipes and ingots cannot guarantee good sealing and waterproof effect when producing rotary tube target. Also, the wall thickness decreases as the wall of the tube is etched. As long as there is a hole connected loosen and sinkhole, the sealing gets worse. The leakage will cause the target tube glows and discharge, or a large amount of miscellaneous gas participates in the reaction, which causing the film falling off or the wrong color of coating. In severe cases, Water is jetted into the vacuum chamber from the shrink hole, which contaminates the true cavity and the vacuum unit.
There are no faults of loosen and shrink holes by the powder metallurgy process. However, from the microscopic view of powder metallurgy, it is also the porous material. Therefore, in order to produce a titanium aluminum rotating tube target, the density of material must be greater than 98. %, but meeting the density requirement does not mean that it can be used. If the titanium aluminum ingot has high oxygen content and unreasonable microstructure, it cannot be used to produce rotating tube target due to the large internal stress. Therefore, there are many requirements for powder production and particle size distribution. Even if the material meets all these conditions, the powder metallurgy titanium aluminum ring must be tied to the stainless steel tube or titanium tube. Due to the large thermal expansion coefficient of titanium aluminum, the local target material expansion may reach 0.5 to 1 m when sputtering, so the traditional binding ingot method cannot effectively solve this problem. There is a phenomenon that titanium aluminum ingots are separated and the heat energy on the target surface cannot be conducted and burst. The tight fitting of the binding ingot is not reliable, and the quality of the plasma-coated titanium aluminum alloy target is poor.
Recently, watches, jewellery and glasses industries require rose gold decorative coating do not contain carbon and make the bottom of the rose is close to the rose gold color on the surface of coatings. Therefore, TiCN has been unable to meet the requirements, and TiAlN is the most perfect solution. Low-end watches and clocks do not have much requirements for film thickness and gloss, so most of them use arc titanium aluminum target to deposit the TiAlN coating, high-end brand watches and clocks require the thickness is 1um or more with high gloss. The arc has no advantage in smoothing the thickness of the film due to droplets. At present, the best way is to use the rotating tube target to deposit TiAIN coating, the color of it is closer to the rose gold, and the gloss is not affected after the thickness is increased.