9 SURFACE TREATMENTS / SURFACE COATINGS Surface treatment / Coating properties examples SurfaceTreaments Color Coating Hardness Thickness Coating Frict. coeff. Max. appl. temp.material[HV][μm]structureagainst steel[°C] ST Dark grey Fe3O4 400 max. 5 Conversion into thesurface – 550 Blue grey TiCN 3000 1 – 4 Multi-layer gradient 0.4 500 Black grey TiAlN 3300 3 Nano structured 0.3 – 0.35 900 Blue grey AlCrN 3200 – Mono-layer 0.35 1100 205