Owing to the constraints of sputter target material manufacture, it is difficult to use certain individual elemental sputter targets for coating deposition (for example, nickel is ferromagnetic - and thus shields the magnets which enhance the sputtering effect; silicon and - particularly - boron are extremely brittle and susceptible to thermal shock). Therefore, to achieve a wide range of coatings incorporating all the elements mentioned above, without complicating and compromising the deposition process, commercially-available (and of proven durability) Al75Ni25 and Ti28Si17B55 sputter target alloys were chosen. The Al-Ni alloy has enough aluminium to produce coatings with the desired high atomic percent of Al, while providing just enough nickel to take advantage of the glass-promoting properties of Ni in combination with Al and other metallic and/or metalloid elements (mentioned earlier). The TiSiB composite sputter target (synthesised using Self-propagating Synthesis, SHS) provides an ideal mixture of large, medium and small atoms of the 'other' candidate elements - and has been used previously in various other sputter deposition experiments by the Surface Engineering group [, , ]. As well as promoting metallic glass formation across a wide range of coating compositions, the combination adds advantages such as high hardness, thermal stability and oxidation resistance. CHAPTER 2: BACKGROUND TO THE DEPOSITION OF PVD COATINGS This chapter covers fundamental concepts and techniques in deposition of PVD coatings. The methods described here are either specific or related to this research. However, a
Owing to the constraints of sputter target material manufacture, it is difficult to use certain individual elemental sputter targets for coating deposition (for example, nickel is ferromagnetic - and thus shields the magnets which enhance the sputtering effect; silicon and - particularly - boron are extremely brittle and susceptible to thermal shock). Therefore, to achieve a wide range of coatings incorporating all the elements mentioned above, without complicating and compromising the deposition process, commercially-available (and of proven durability) Al75Ni25 and Ti28Si17B55 sputter target alloys were chosen. The Al-Ni alloy has enough aluminium to produce coatings with the desired high atomic percent of Al, while providing just enough nickel to take advantage of the glass-promoting properties of Ni in combination with Al and other metallic and/or metalloid elements (mentioned earlier). The TiSiB composite sputter target (synthesised using Self-propagating Synthesis, SHS) provides an ideal mixture of large, medium and small atoms of the 'other' candidate elements - and has been used previously in various other sputter deposition experiments by the Surface Engineering group [, , ]. As well as promoting metallic glass formation across a wide range of coating compositions, the combination adds advantages such as high hardness, thermal stability and oxidation resistance. CHAPTER 2: BACKGROUND TO THE DEPOSITION OF PVD COATINGS This chapter covers fundamental concepts and techniques in deposition of PVD coatings. The methods described here are either specific or related to this research. However, a
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