Materials Type: Harder resources gain from the sharper silicon carbide, whilst softer components and finer finishes are better accomplished with aluminum oxide. Dec 28, 2018 #seven The flat surface doesn't need to be glass, in truth glass is not that hard. It may be nearly anything rather hard and flat. http://cristianoojs975.wpsuo.com/10-startups-that-ll-change-the-silicon-carbide-igbt-industry-for-the-better