チタン被覆について

金属粉末による鋼板の被覆 (第1報)

抄録

With the object of coating titanium on mild steel sheet, a novel method was investigated by the authors. The method consisted of the following processes; at first, applying titanium powder on the mild steel sheet previously treated with adhesives, drying, pressing the powder on steel by rolling, and sintering the titanium layer in vacuum for bonding it with steel. Aqueous solution of potassium polymetaphosphate was used as adhesives. Sintering was carried out at 900-1000°C. The coating layer was about 25μ in thickness, but it was about 50μ when the powder was applied 2 times. The coating layer was continuous and revealed good adhesion to steel. The corrosion rates of the layer at room temperature were lower than the following values, respectively; 0.063mm/year in 10% HNO₃, 0.053mm/year in 1% H₂SO₄, and 0.0047mm/year in 3% aqueous NaCl solution.
Workability was tested by bending the coated sheet over mandrels of various diameters. Fine cracks were observed on the coating layer when the coated sheet was bent over a mandrel of less than 140mm in diameter. It was found that such formation of cracks was caused by the hardening of the coated titanium layer due to the diffusion of Fe from the substrate. Such phenomena of diffusion were confirmed by electron probe X-ray microanalysis and X-ray diffraction.