Adhesion

Adhesion is the strength of the bond of the coating to the substrate. Adhesion can be measured in several ways, such as: Daimler-Benz Adhesion test (see), Scratch Adhesion test (see), Tape test (see), and Stud-pull-off test (see).

Cohesion

Cohesion refers to the strength of the material to support itself. As opposed to adhesion (see). Adhesion failure happens when one layer delaminates from another, cohesion failure is when the delamination occurs within a material.

CVD

Chemical Vapor Deposition. A coating deposition process that is characterized by a chemical reaction producing the desired film material. CVD processes are usually performed in vacuum, but not always. Vacuum CVD processes generally are not performed in high vacuum conditions (as used in PVD processes). Many CVD processes are performed at elevated temperatures. Hard coatings […]

Daimler-Benz Adhesion Test

A method of checking the adhesion of PVD coatings that relies on observation of a Rockwell C indent. The stresses around the rim of a normal Rockwell C indent can cause microcracking and delamination of the coating. Because these stresses are greatest at the rim of the crater and then taper off radially outward, the […]

Delamination

Delamination refers to the separation of the coating from the substrate. It can also refer to separation between multiple layers of coating or even to cohesive failure of a coated part.

Elastic Deformation or Elastic Hardness

Refers to a temporary deformation of the material in response to an applied force. As the force is removed the elastic deformation recovers or springs back. As opposed to “plastic deformation or hardness” (see). I

Fretting

Wear caused by low amplitude motion between parts. Usually occurs in parts that are not designed to be moving relative to each other, but move because of vibration.

Hardness

The ability of a material to resist deformation. Generally “plastic deformation” (see) is the measured property, but in some cases “elastic deformation” (see) is also of interest.

Plastic Deformation or Plastic Hardness

Refers to a permanent deformation of the material in response to an applied force. The part will be deformed and the deformation will remain after the load is removed. As opposed to “elastic deformation or hardness” (see) where the material springs back to it’s original shape. In general, a material can have both plastic and […]

Pressure

The measurement of the force exerted by a medium on the objects in the medium. In vacuum coating, pressure refers to the pressure of the gases in the vacuum chamber. Pressure is normally measured in Torr. Other units are psi, bars, atmospheres, pascals, etc.

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