Titanium Surface By Ion Beam Assisted Deposition Of Wear, Corrosion Resistance Coating Study

Titanium alloys are applied widely in aeronautic industry because of their outstanding properties of high strength/weight ratio, thermal stability and corrosion resistance. However, titanium alloys suffer from the serious disadvantages of poor tribological properties which affect service life and safe reliability of engineering components. Aim at improvement of titanium alloy tribological properties, several types of alloy coatings and lubricating non-metallic coatings were prepared using ion beam assisted deposition (IBAD) technique and closed filed unbalance magnetron sputtering ion plating (CFUMSIP) technique which have some advantages such as avoidance of hydrogen embrittlement and obtaining high coating bounding strength on the active metal materials surface. The basic characteristics and tribological properties of the coatings prepared by [BAD and CFUMSIP techniques were evaluated in order to provide experimental data and guide to aeronautic engineering application. The coatings studied in the present paper include alloy coatings respectively made of Cr, CrMo alloy, 0Cr18Ni9, CuNi alloy, QA19-4 and NiCr and non-metallic coatings such as graphite-like carbon (GLC) coating and MoS₂-Ti (MoST) composite coating. The microstructure, morphology, constituent distribution, hardness and bonding strength of the coatings were studied by using X-ray diffractometer, scanning electron microscopy, glow-discharge photo-electron spectroscopy and micro-hardness tester respectively. The wear resistance and electrochemical corrosion properties of these coatings were investigated with ball-on-disk wear tester and electrochemical equipment, respectively. Some contributions had been obtained as follows:1) The denser and nanometer crystalline coatings of Cr, Cr-Mo, 0Crl8Ni9, NiCr20, CuNi62, CuNi38 and QA19-4 with higher bonding strength have been prepared on titanium alloy surface by IBAD method. Surface hardness of those coatings is HK2410, HK2000²300, HK900¹100, HK820, HK780, HK675 and HK540 respectively. The wear resistance properties of Ti6AI4V alloy are significantly improves by those IBAD coatings due to their high surface hardness. IBAD Cr, CuNi38 and QAI9-4 coatings show anti-wear property and low friction coefficient, while the rest coatings among them show anti-wear property only.2) IBAD Cr, Cr-Mo, 0Cr18Ni9 and NiCr20 coatings are cathodic coatings relative to titanium alloy substrate and have good electrochemical corrosion resistance, low galvanic corrosion sensitivity and excellent contact compatible with titanium alloy in containing Cl solution, while IBAD CuNi and QA19-4 coatings as cathodic coatings are compatible contact with titanium alloy substrate in containing Cl' solution.3) IBAD 0Cr18Ni9 stainless steel coating, NiCr20 coating and QA19-4 coating have high ductility, while IBAD Cr coating, Cr-Mo coating and CuNi62 coatings show low ductility.4) It was found that the graphite-like carbon (GLC) coating synthesized by IBAD technique was characterized by sp2 hybridization and had good coverage, uniform distribution and fine grain. High hardness and low friction coefficient endow the coating excellent tribological properties, while the lubricating property of the GLC coating degrades at temperature 350℃ due to destabilization of the structure and mechanical properties of the coating.5) The uniform and fine crystalline MoST coating with high bonding strength, high hardness and high density was prepared using unbalance magnetron sputtering ion plating. With Ti co-deposition content in the coating increases, the hardness increases and the ductility decreases. The MoST coatings possess remarkable low friction coefficient of 0.10⁰.15 and performance more excellent tribologicalproperty than pure M0S2. The MoST coatings have high corrosion resistance and good compatibility contact with titanium alloy in containing Cl solution.6) The investigation of bonging strength of IBAD CuNi62 coating on Ti alloy substrate influenced by interlayer metal including Ni, Ti and Cr indicated that Ti interlayer is the best choice amon...