Premazi visokog sjaja - uticaj hrapavosti površine na sjaj

Abstract

Očvrsnuo film premaza uvek sadrži određene nepravilnosti koje su posledica postupka i uslova nanošenja. Iz tog razloga u cilju postizanja visokog sjaja lakirane površine, uz primenu premaza visokog stepena sjaja neophodno je poliranje lakirane površine tj. brušenje lakirane površine vrlo sitnim brusnim zrnima. U ovom radu ispitano je kako pojedine faze procesa poliranja utiču na hrapavost lakirane površine i stepen sjaja. Hrapavost lakirane površine izražena je parametrima: Ra; Rz i Rt; a sjaj lakirane površine je određen primenom dve geometrije merenja: 20o i 60o.Utvrđeno je da kroz faze poliranja hrapavost lakirane površine opada, a stepen sjaja raste. Visoka vrednost koeficijenta determinacije (R = 0,984) pokazala je da postoji linearna zavisnost između parametra hrapavosti Ra i sjaja lakirane površine (mereno pod uglom od 60o). Primena dve geometrije merenja (20o i 60o) je potvrdila potrebu primene geometrije od 20o kada se određuje sjaj visoko sjajnih površina, jer standardna geometrija od 60˚ ne obezbeđuje sagledavanje malih razlika u stepenu sjaja koje nastaju kao posledica poliranja.

The cured finishes always contain certain irregularities that result from the technique and conditions of application. For this reason, in order to achieve smooth high gloss finished surfaces, it is necessary to polish ('rub-out') surfaces coated with high gloss finish. Rubbing means sanding the finished surfaces with very fine abrasive grits. In this paper we explored how each phase of the polishing process affect the surface roughness and the gloss of coated surface. The surface roughness was expressed by the parameters: Ra, Rz and Rt, and the gloss was determined by reflectometer (measurement angles 20˚ and 60˚). The results showed that through the stages of polishing, surface roughness decreased, while gloss of finished surface increased. The high value of the coefficient of determination (R2 = 0,984) indicated the linear dependence between the roughness parameter Ra and gloss of finished surface (at measuring angle of 60˚). The comparison of gloss results obtained by two measuring angles, confirmed the need for using the angle of 20˚ when determining the gloss of high gloss surfaces, since universal angle of 60˚ did not provided insight to small differences in the gloss that appeared as a result of polishing.