Study On Preparation Of High Temperature Oxidation Resistant Coatings And Its Reaction Diffusion Modification Process

Oxidation of metallic materials is a very common form of material failure,especially at high temperatures.Alloys or metals commonly used in the industry are oxidized to form oxides at high temperatures,and as the oxidation progresses,the metal elements in the materials are continuously consumed,causing the failure of the materials.Thermal spraying can effectively avoid oxidation of working parts at high temperatures.In high temperatures,the workpieces are easily exposed to high temperature oxidation and corrosion,which shortens the service life of the workpiece and seriously affects product quality and work efficiency.The use of thermal spraying to prepare a single metal coating or composite metal coating on the surface of the workpiece can effectively improve the service life of the workpiece.In response to these problems,scholars and institutions at home and abroad have also conducted corresponding research and reports.However,most of them introduce the oxidation reaction diffusion process of a certain coating at a certain temperature.It is systematically studied that the results of reaction expansion of various coatings at multiple temperatures are relatively small.In this paper,the reaction diffusion process of pure aluminum coating and Ni/Al composite coating prepared on TA1 at different temperatures and different times were investigated,and compared with uncoated TA1 block,meanwhile,drew an oxidative weight gain curve and a cross-section oxygen element scan.Research indicates,the pure aluminum coating formed a corundum-typeα-Al₂O₃ protective film on the surface of the coating at 700℃,800℃and 900℃;In addition,the Al coating was tightly bound to the matrix TA1,and as the temperature and the heating time increased,the transition layers appear at the junction and the number of layers increased;According to the analysis,most of the oxidation-resistant Al-rich titanium-aluminum intermetallic phase was mainly TiAl₃ phase with strong oxidation resistance.The Ni/Al composite coating also formed a corundum-typeα-Al₂O₃ protective film at the experimental temperature;In the interior of the coating,Al and Ni interdiffused to produce a nickel-aluminum intermetallic compound,mainly an oxidation-resistant NiAl phase and a Ni₂Al₃ phase,and a small number of NiAl₃ phases existed;As the temperature rises and the time increases,Al has diffused to the surface of the matrix TA1 and reacted with the Ti element to form a transition layer,which was the same as the mechanism of the pure Al coating to form a transition layer,and was also a transition layer mainly composed of a TiAl₃ phase.It is precisely because the Al-rich composite coating in the Ni/Al composite coating is more resistant to oxidation,and the pure Al coating is superior to the uncoated TA1,and the Ni/Al composite coating has significantly improved oxidation resistance compared to the pure Al coating were confirmed by the oxidation kinetic curves and the cross-section oxygen surface scannings.