tailieunhanh - Substrate and Coating Erosion_2

Tham khảo tài liệu 'substrate and coating erosion_2', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 176 5 Substrate and Coating Erosion Fig. Effect of oxidation temperature on the adhesion of oxides to the metal substrate Engell 1960 of hardener concentration and coating Fig. Effects Fokke 1999 thickness on Young s modulus Mechanical Properties of Oxides and Organic Coatings 177 the strain relative elongation of more than 30 epoxy-based organic coatings are listed by Askheim et al. 2001 . Values for fracture toughness and yield strength of an epoxy coating are shown in Fig. as functions of temperature. Impact resistance of coatings is often described in terms of an energy required to penetrate a coating layer of defined thickness. A ranking of different coating materials for a drop weight test is as follows polyethylene 30 Nm polyurethane 20 Nm tar epoxy 5 Nm Sato et al. 2003 . Erosion processes are associated with high strain rates Hutchings 1992 which affect materials properties as well as the deformation responseofthecoating materials. AnexampleisprovidedinFig. showinganotable increase in yield stress for three polymers for high strain rates. A review on the affects of strain rate variations on mechanical properties of polymer materials was provided by Siviour et al. 2005 . The authors also noted significant effects of the temperature on mechanical properties. Storage modulus and peak stress measured during high strain rate loading decreased with an increase in temperature. Values for a number of mechanical properties of organic coatings are listed in Tables and . Hardness Hardness values measured on organic coatings were provided by Fokke 1999 Gnyp et al. 2004 Kotnarowska 1999 Neumaier 1993 Pickles and Hutchings 1997 Rehacek 1982 and Tangestanian et al. 2001 . Some results are provided in Tables to . It can be seen that hardness depended on temperature - it usually increased with an increase in temperature. For comparison a hardness value for steel as a typical substrate material is provided. Vickers hardness of .