Mechanical properties of borosilicate glass coated with pure aluminum by sputtering

Borosilicate glass was coated with pure aluminum by the radio frequency (RF) magnetron-sputtering method under various conditions. The mechanical properties of coated materials were investigated with respect to the sputtering conditions. The surface roughness (R-a) and porosity (p) measured on the coating increased when the initial temperature of the substrate (T-si) was increased. A positive correlation between R-a and p also was confirmed. The hardness of aluminum-coated material was measured by using a Vickers microhardness tester. The hardness was greater in materials processed at higher T-si, although the hardness hardly depended on the RF output power, P-RF. However, the hardness of materials coated under every condition was inferior to that of the substrate glass. Strength tests of coated materials and the substrate glass also were conducted under three-point bending mode. The bending strength (sigma(fm)) of the coated material decreased with increasing T-si, although it was better than that of the substrate glass. A good correlation between sigma(fm) and hardness was observed for coated materials, irrespective of the sputtering condition.