Cubic (c-) BN thin films including an sp2-bonded phase were prepared by controlling the substrate potential and H2/N2 flow ratio in the plasma chemical transport (PCT) of boron from boron powder. In this chemical vapor deposition (CVD) process, it is not necessary to use dangerous materials such as boron hydrides or organic boron adducts which contaminate films. We found that 800°C was the most suitable substrate temperature for c-BN growth in our experiment. Both rates of the formation of sp2-BN and of its sputtering by energetic nitrogen ions were greater than those of c-BN. The N/B ratio of the film gradually decreased from a stoichiometric composition (N/B=1) when the substrate was negatively biased. The hydrogen content in the plasma must be as low as possible with a suitable bias voltage impression to the substrate, because energetic hydrogen ions have the possibility of chemically interrupting the formation of c-BN and etching BN deposits.
The solder plating posttreatment we developed involved immersing the plating film in a tin fluoborate solution and substituting tin for lead as follows: Sn2+(L)+Pb(s) High temp._??_Low temp.Sn(s)+Pb2+(L) where (L) indicates “in solution” and (s) indicates “in solder film”. Increasing the concentration of Sn2+ and the temperature reversed the redox potentials, M2++2e_??_M, toward less noble Sn making the forward reaction dominant. This treatment produced a smooth surface lustrous and enriched in tin content in the outer portions of the film. This resulted in a marked inprovement in antioxidation properties, adhesion to the basis metal, solderability, and heat-humidity stability. Enriched lead in the bath due to the multitreatment was easily removed as PbSO4 precipitate by adding sulfric acid.
Grade 13 (Ti-0.5%Ni-0.05%Ru), specified in American Society for Testing and Materials (ASTM) Standards, can be used in place of Grade 7 (Ti-0.15%Pd) due to its excellent corrosion resistance and high cost-performance. We studied corrosion surfaces of Grade 13 annealed at different temperatures to clarify the mechanism of active dissolution. Ti2Ni particles containing ruthenium were observed prior to corrosion tests on the surfaces of Grade 13 annealed in the α-phase. Only pits remained after corrosion tests, however, because particles were removed from the surface by hydrogen evolution shock. In α+β-phase, annealing, the β phase was selectively attacked and the corrosion rate increased. In case of β-phase annealing, the corrosion surface showed an acicular pattern and the corrosion rate was highest among the tested samples. To minimize the corrosion rate, Ti2Ni particles containing ruthenium should be precipitated finely in matrix which results in the enlargement of cathodic area and thus prevents particles from the detachment.
The grit holding force of the electrodeposited layer on a diamond wheel is known to be very strong, but remains to be evaluated quantitatively. The influences of electrodeposition conditions on the holding force also remain to be clarified. Our objectives were to obtain the maximum grinding force applied to single grit wheels produced under different conditions of electrodeposition and to obtain basic data for the production of electrodeposited diamond wheels. The mean diameter of the diamond grit used in our experiment was 120, 250, and 400μm. The current density in electrodeposition was 3, 5, and 7A/dm2. The ratio of the embedded layer depth to the grit diameter was 30, 50 and 70%. We found that the grit holding force of the layer was proportional to the projected area of grit in the horizontal direction and that the current density in electrodeposition had no effect on the grit holding force.