Deposition Of New Nanocomposite Coating By Plasma Enhanced Magnetron Sputtering

Nanocomposite coatings have been studied extensively and have been foundmany potential applications to protect components in industry including automobileparts, cutter, moulds, various engine, and optical glass from high temperature,corrosion and fatigue. In this thesis, Plasma Enhanced Magnetron Sputtering(PEMS) method was used to deposit Ti-based, TiCr-based, and TiAl-basednanocomposite coatings on H13steel. The work was focused on the influences ofthe composition (Cr, Al, C, and O) on the microstructure and properties of thecoatings including the hardness, adhesion, surface energy, high temperatureresistance, erosion and corrosion properties. The main results obtained from thisstudy are summarized as follows:(1) The coatings made by PEMS are generally dense with a minimum columnstructure. Thus, the surface roughness is very low. It is clear that in the PEMSprocess the heated tungsten filaments could generate more plasma, which densifiesthe nanocomposite coating.(2) The oxygen-free coatings show a dense microstructure without the typicalcolumnar feature that is commonly observed in plasma enhanced magnetron sputterdeposited films. When oxygen is added, the nanocomposite coating becomesslightly rougher with bigger particles on the surface. It shows a column structurewith a few pores. This microstructure has a negative effect to the coatingmorphology. However, the adhesion test shows that the addition of oxygenimproves the adhesion between coating and substrate. The surface energymeasurement indicates that the surface energy of Ti based and TiAl based coatingsis lower with the addition of oxygen than all other coatings. As for the Crcontaining coatings, the surface energy is influenced by the surface topography.(3) Comparing all the coatings the microhardness measurement shows thatH(TiCr based)＞H(TiAl based)＞H(Ti based), indicating that a multi-elemental coating canimprove the coating hardness. The nanohardness test shows that Ti based coating istougher while TiAl based coating is even tougher with the oxygen addition than allother coatings. However, the toughness of TiCr-based coatings decreases with theaddition of oxygen.(4) The slide friction wear test shows that the friction coefficient of nanocomposite coating with Cr is high. But if a coating has a higher concentrationof carbon, the coefficient of friction becomes lower. According to the abrasion loss,hardness could dramatically strengthen the wear properties. The erosion test showsthat all coatings improve the erosion resistance over the uncoated H-13by3~11.Moreover, the coating with oxygen exhibits better anti-erosion resistance.(5) The XRD and EDS results show that amorphous aluminum nitride andaluminum oxide exist in the coating, especially for the TiAl-based coating, whichshows very good high temperature oxidation resistance.(6) The study on the corrosion properties of the nanocomposite coating andmatrix H13steel shows that the nanocomposite coatings markedly improve thepolarization resistance of the substrate. Among all coatings the coatings withoxygen exhibit poorer corrosion resistance. This is related to the defects of thecoating. On the other hand, a thicker coating can improve the corrosion properties.Moreover, the polarization resistance of the coating increases with the addition ofTi and Al, while the TiAlSiCN nanocomposite coating shows the best corrosionresistance. In contrast, Cr-contained coating shows a poor corrosion behavior.