PVDPhysical vapor deposition, material is transported as vapor from a target to the product. Reactive elements like N2 are often added from the gas phase. The deposition temperature ranges from room temperature to 550 °C.
CVDChemical vapor deposition, material is exclusively taken from the gas phase, metal atoms are normally carried by complex molecules. Reactive elements like N2 are added from the gas phase. The substrate temperature is typically between 800 and 1050 °C.
PACVDPlasma assisted chemical vapor deposition, material is exclusively taken from the gas phase, but the process temperature is lowered to levels between 200 and 550 °C.
CVAChemical Vapor Aluminising is a process used to diffuse aluminium into the surface of a part in order to enhance temperature corrosion and oxidation resistance.
DLC, diamond like carbonnomenclature according to the VDI 2840 standard is:
- a-C:H amorphous hydrogenated carbon with mix sp2/sp3
- ta-C:H amorphous hydrogenated carbon with sp3 as the dominant binding
- ta-C amorphous non-hydrogenated carbon with sp3 as the dominant binding (Tetrabond™)
ADLCAmorphous Diamond Like Carbon, an Ionbond coating whereby a-C:H is produced in a Radio Frequency plasma. The advantage of ADLC is that non-conductive substrates can be coated.
AdhesionAdhesion is normally classified by Rockwell indentation, a diamond with tip-radius of 200 µm and cone angle of 120° is indented with a standard force (0.5 N). The image is analysed and results in a classification of HF1 to HF6. The measurement is semi-quantitative. The measurement does not result from the binding between surface and first coating layer, but the mechanical response of the coating plus substrate under load.
The adhesion test is carried out in accordance to VDI 3198
HardnessThin films generally have a hardness much higher than the substrate. Classical hardness tests rely on a deep indentation. For thin films, the film hardness can only be determined accurately by means of an indentation depth considerably less than the film thickness. The standard hardness tests used is the Vickers Hardness test whereby a pyramid shaped diamond is applied with a standard load of e.g. 20 mN.
ThicknessThe thin film thickness typically ranges from 0.5 µm (decorative coatings) to 10 µm (CVD coatings). The film thickness is determined by means of a ball crater (calotest) on a coupon whereby the coating thickness can be calculated based on the resulting crater image measurements.
Friction coefficientFriction coefficients can be measured in many ways. Generally the friction coefficient is measured without lubrication in a normal air atmosphere and against an uncoated standard steel plate.
Surface roughnessSurface roughness is characterized by up to 6 parameters. The following two are generally considered the most relevant:
- Ra, the average surface roughness measured over a length of 40 mm
- Rp, the maximum peak height