Coating yield strength

Upon re-heating, regions of tensile stress may develop in the TGO. With an increase in the number of thermal cycles, the shear stresses induced in the bond coat upon cooling exceed the bond coat yield strength, so that it flows plastically from valleys to peaks at the undulation sites, allowing the undulation amplitude to increase (Fig. 11). As a result, the normal tensile stresses increase and ultimately lead to separation of the TGO [69]. 

Tensile properties of importance include the modulus, yields, (strength at 5% elongation), and ultimate break strength. Since in many uses the essential function of the film may be destroyed if it stretches under use, the yield and values are more critical than the ultimate strength. This is tme, for example, where film is used as the base for magnetic tape or microfilm information storage. In some cases, the tensile properties at temperatures other than standard are critical. Thus if films are to be coated and dried in hot air ovens, the yield at 150°C or higher may be critical. 

Below yield strength of the metal, coating of liquid metal has no effect whatsoever on the mechanical properties of the metal. 

A bar of 5 mm diameter made of high strength steel (yield strength = 1100 MPa) is subjected to a tension force of 1.5 x 10" N. Indicate if the bar will withstand this force (a) in a non-corrosive environment and (b) in the presence of dissolved hydrogen resulting from a bad zinc coating (cf. Fig. 11.27). 

The indentation confidence depth was determined to be a function of the coating to substrate yield strength ratio for three different substrate configurations. Tilbrook et al. (2007) incorporated microstructural failure mechanisms into finite element simulations of nanoindentation of TiN thin films on elastic—plastic substrates. Intergranular sliding that occurs as a result of the columnar grain structure is incorporated into the model via anisotropic property definitions and nodal coupling. 

OZ Orgtinic zinc coating SMYS Specified minimum yield strength... 

Unalloyed steels without coatings or protective films are widely used for the reinforcement of concrete buildings [7]. Their required mechanical strengths are specified in DIN 1045 [8]. Common designations are concrete steel I-IV with minimum yield strengths of 220 to 500 N/mm (special reinforced concrete) and tensile strengths of 340 to 550 N/mm. ... 

Manufacturers literature offers recommendations on estimating optimum coating levels, and in practice it is usually best to test several coating levels so that the required properties can be optimized. Even the concept of optimum properties is not straightforward, as illustrated in Figure 4 for a compound containing stearic acid coated calcium carbonate in polyethylene. While yield strength is at a maximum... 

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