The natural oxide layer worked as an etching mask at 25 min. While the heights of the pre-processed areas were exactly the same as those before etching, the area
pre-processed at 40-μN load was enlarged by the plastic deformation.Figure 12 shows the topography and cross-sectional profiles of the pre-processed areas after 30-min etching. The etching also advanced in the unprocessed area. The etching depth of the area processed at 1.5 μN progressively increased to 210 nm, while that of the unprocessed area increased to 140 nm. This implied that only the Selleck Pevonedistat high-loaded processed area was not etched because of the mechanochemical oxide layer. The height obtained RG-7388 order at 10-μN load was slightly higher than that at 40-μN load.Figure 13 shows the etching profile of pre-processed areas after 40-min etching. The etching depths of both the low-load processed and unprocessed areas were approximately 530 nm. In contrast, the areas processed at high loads of 10 and 40 μN were not etched. This experimentally confirmed that high-loaded processed protuberate areas show superior etching resistance towards
KOH solution due to formation of a high-density OSI-906 purchase oxide layer.Figure 14 shows the dependence of relative etching depth on KOH solution etching time. The standard plane is the unprocessed area. The plane heights of the areas pre-processed at 10- and 40-μN load from the standard plane are denoted as A and B. The corresponding height of the area pre-processed at 1.5-μN load is C. Between 10 and 20 min, there was little change in the topography of each area. From 25- to 30-min etching, it was observed that the etched depths significantly increased in the 1.5-μN-load pre-processed area. However, etching was hardly observed in the 10- and 40-μN-load
pre-processed areas. Etching of the unprocessed area was hardly observed until 25 min. After 30-min etching, the unprocessed area was progressively etched owing to the removal of the natural oxide layer. Figure 10 Etching profile of processed parts after 20 min. (a) Surface profile. (b) Section profile (10 and 40 μN). Figure 11 Etching profile of processed parts after 25 min. (a) Surface profile. (b) Section RVX-208 profile (10 and 40 μN). Figure 12 Etching profile of processed parts after 30 min. (a) Surface profile. (b) Section profile (10 and 40 μN). Figure 13 Etching profile of processed parts after 40 min. (a) Surface profile. (b) Section profile. Figure 14 Dependence of relative etching depth on etching time at different loads. From 35 to 40 min, the etching depths of both the unprocessed and 1.5-μN-load pre-processed areas were larger than those of the areas processed at higher load. The area mechanically pre-processed at higher load exhibited resistance to etching owing to mechanochemical oxidation layer formation.