Tham khảo tài liệu 'surface engineering of metals - principles, equipment and technologies part 17', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Non-metal coatings particularly paints varnishes and enamels are used to coat rather big objects which are exposed to only small mechanical hazard. Exceptions to this rule are ceramic enamel and metal ceramics which can sustain high mechanical loads. Classification of coatings by application From the point of view of application coatings can be divided into four groups 1 4 protective decorative decorative-protective and technical. Protective coatings Protective coatings are those coatings whose task is exclusively protection of the object from the harmful effect of the environment mainly the atmosphere and chemicals as well as from mechanical hazards. These coatings may also feature properties other than anti-corrosion . higher hardness resistance to tribological wear or attractive appearance. These however are properties of secondary importance. Since they protect the object from different types of corrosion they are sometimes referred to as anti-corrosion coatings. From the point of view of service life protective coatings may be classified as temporary and permanent protection coatings. Coatings for temporary protection serve to secure mostly metals against corrosion during transport or storage as well as during interoperational periods before the product goes into service 1 . Most often these are coatings easily removed by stripping grinding down or washing off. Their composition is based on . oils greases asphalts waxes some varnishes and some plastics 26 27 44 45 . Temporary protection is also assured by tight packaging with the use of solid liquid or gas corrosion inhibitors 26 27 . Coatings for permanent protection serve to secure the surfaces of products during service. These are the majority of metallic coatings and many paints varnishes and enamels metal ceramic ceramic rubber and latex. The protective function of coatings may consist either of only insulation of the coated object from the environment or by electrochemical interaction
