Characteristics of Ti-Based High-Temperature Thermally Stable Coating Films

摘要

Aluminum has higher activity under high-temperature die casting process. Aluminum easily reacts with mold (die) materials, causing sticking. In the repeating thermal impact die casting process, molds are subjected to a large thermal difference, which causes sticking and corrosion damage, thus degrade their surface precision and mechanical properties. To prevent the sticking of molds, a mold-releasing agent should be sprayed each molding cycle. This study deposits Ti-based coating films on DAC53 hot working tool steel substrates using the direct-current magnetron sputtering process. High-temperature resistant lattice atoms such as tungsten, tantalum, and aluminum are added and reactive nitrogen gas is injected. Scanning electron microscopy, grazing incidence X-ray diffraction, transmission electron microscopy are used to analyze the surface morphology, crystal structure, and chemical bonds. Thermal cyclic experiments are conducted to test the thermal stability of the coating thin films. Results show that Ti-based high-temperature coating films effectively improve the thermal stability of DAC53 substrates at 800℃. Practical in-line tests at 800℃ show that the thermal cyclic test can reach 500 cycles without using a mold-releasing agent.