Surface hardness evaluation of components made by color stereolithography

Surface hardness value is a commonly used indicator for describing the mechanical property of stereolithography parts. In order to investigate colorants how to influence the surface hardness of colorful resin component, a procedure is proposed to fabricate testing specimens based on color stereolithography technology in this study. Liquid photosensitive resin LPR2001 is mixed with two colorants （phthalocyanine blue and eosin powder） respectively before curing. The phthalocyanine blue powder is insoluble and only dispersive in the solid- liquid mixture which results in deposits. Therefore, surface modification is conducted to the phthalocyanine blue powder for improving wettability. By contrast, the eosin powder is dissoluble and does not cause any deposits in the liquid resin. Specimens are produced by laser curing colored resin and tested by MTSR Nano Indenter XP system. The change of hardness values is illustrated at certain mass percentages of colorant. Comparisons and discussions are carried out to explain the colorants＇ effect. It is concluded that incorporating colorant to liquid resin results in decreasing the surface hardness of components. But sensibilization effect of the colorants also influences the curing process. Surface modification to the phthalocyanine blue powder is a feasible method to increase the hardness value of color stereolithography components. Dissolvable eosin has an approximate linear effect on surface hardness.