Advances in Surface Engineering technologies enable surfaces with improved hardness, superior wear resistance, friction behaviour, heat resistance and corrosion characteristics without altering the desired bulk mechanical properties. Many mechanical systems operate under severe application conditions such as intensive loads, high speeds, and harsh environments leading to complex design situations requiring several properties such as wear resistance, load bearing capacity and fatigue performance. These new challenges can be met through realising potential of surface engineering involving duplex, multilayer or graded interfaces. TiN, Ti(C,N), (Ti,Zr)N, (Ti,Al)N coatings deposited by various Physical Vapour Deposition techniques offer hard, superior oxidation and wear resistance coatings for various commercial applications. (Ti,Al)N coatings are most desirable in dry machining and machining of abrasive alloys at high speeds. Variants of these coatings involving multi components by adding different alloying elements further enhance their properties for specific applications. Such as Chromium and Yttrium improve the oxidation resistance, Zirconium and Vanadium improve the wear resistance, Silicon increases the hardness and resistance to chemical reactivity, Boron improves the abrasive wear resistance by forming hard TiB2 and BN phases. Hafnium based nitrides and carbides have potential for resistance to flank and crater wear. Multilayer coatings of these compounds further enhance their property values. These all are promising candidates for future application of coatings in various fields and therefore need to be studied in a systematic manner. The long term viability of machine components operating at higher temperatures in oxidising environment often relies on the integrity of a thin, protective layer of oxide, typically Chromia, Alumina or Silica. High performance die coatings and self healing oxidation resistant coatings are other examples. Understanding the mechanisms of the formation of such a protective layer and the processes, which affect its mechanical integrity are major challenges. Chromium oxide as well as Diamond Like Carbon (very thin) coatings of 20-40 nm thick are useful for linear data tape advanced digital recording heads for improved wear resistance.Plasma Nitriding of HSLA steels, Plasma Nitrocarburising of ferrous substrates, plasma surface alloying of Austenitic Stainless Steels, surface engineering of Iron Aluminides and Titanium Aluminides for enhanced wear and other properties are the other areas of research in surface engineering which needs to be studied further. Surface engineering of Biomedical Materials is an interesting field for future study. Calcium phosphate coatings are biological similar to bone apatite, mimicking the properties and are therefore, interesting to study. The duplex treatment involving the plasma nitrided steel system with over coat of DLC coatings or nitride based compound coatings offer another interesting field for improved properties of various components. Composite coatings involving metal-ceramic mixtures produce tough coatings by spray techniques.Chrome coatings, due to their hazardous plating baths are being done away because of the stringent norms being followed by Governments.
Therefore, various options are being explored to replace these coatings. Cr & CrN coatings by PVD techniques is one such option. Besides spray coatings involving WC-Co, CrC-NiC, SS316, NiCrBSi are being considered as replacement for chrome for various applications.Potential approach for reducing the level of nuclear plant radiation exposure from activated co wear debris is the use of a wear resistant coating. A thin layer of Cr-N coating or for better results use of the duplex approach - nitriding the subsurface followed by a thin Cr-N top layer is useful. Valve seats and stems used in nuclear power plants similarly could also be coated with Al2O3/TiN/TiC, Al2O3/TiC and TiN/TiC or Cr-N using PVD or CVD techniques onto Stellite. Laser cladding method produces a highly corrosion resistant coating SiC layers on the inner surface of SS-304 pipes to prevent Stress Corrosion Cracking. With the decreasing costs lasers will soon become a familiar part of the industrial landscape. Aluminium coatings are finding applications on the collimator heads used in cyclotron proton beam lines. Similarly niobium coatings are under development stage for resonators. Multicomponent (TiAlSi)N, TiBN and other superhard, nanocomposite coatings are finding their way into dry milling, drilling and possibly turning applications and due to their fast development will find many further potential applications in the future. A better understanding of the tribological behaviour of engineered surfaces is the key to the future success of the many new (e.g. MEMS) and old (e.g. machinery, tools, and automotive industries) Various techniques employed to deposit these coatings are Magnetron Sputtering, Electron Beam Evaporation, Ion-Plating, Cathodic Arc Deposition, Plasma CVD etc. MOCVD (Metal Organic CVD) is another technique for deposition of compound coatings. ZrN, Zr(C,N), Zr(O,N) are of technological interest as wear resistant coatings with improved tribological properties compared to TiN, as diffusion barriers in microelectronics and in sensor technology.Diamonds have impressive properties-unsurpassed hardness, outstanding heat conductivity and transmission of X-rays and laser beams. Diamond discs formed by CVD are suitable as windows for lasers and microwave generators, as base plates for electronic components and as cooling elements for power electronics and optoelectronics.Few micron thick Luminescent layers deposited form phosphors having high uniformity, as well as ultra high resolution, high luminous efficiency, optimum contrast and lifetime is another field of interest.