Metal (Cr, Ti, Si) thin films were prepared by evaporation and ion plating, the influence of argon gas pressure, deposition rate and substrate bias voltage on their crystal orientation and morphology was investigated. Although the crystal structures of films differed, the changes in their preferred orientation and morphology showed a similar tendency. Films deposited at low argon gas pressure exhibited low surface energy face orientation and a columnar structure. The relative intensity of high surface energy face increased with increases in argon gas pressure. The diffraction peaks of the films became weak and broadened as argon gas pressure became excessive. Film morphology changed from columnar to granular as argon gas pressure increased. It was concluded that metal films exhibiting a fine grannular structure can be obtained by the PVD method at high argon gas pressures. The orientation and morphology of the films were also influenced by deposition rate and substrate bias voltage. The change in film orientation was explained by an adsorption model.
The effects of selected gases readily available as carbon sources, -including propane, butane and alcohols-on diamond deposits on Si wafers by microwave plasma CVD were compared in terms of rate of deposition efficiency and cost. The maximum deposition rate for C3H8-H2 system was 1.5 times faster than that of CH4-H2, while those of the C6H6- and C2H5OH-H2 systems were two times faster, but it was not possible to obtain rates proportional to carbon densities. At corresponding C/H ratios in each gas, hydrogen-diluted LPG′ gas can achieve a deposition rate comparable with methane and at reduced cost of a factor of up to 8. Alcohols and other compounds containg oxygen provide higher controllability and a wider range of usable concentrations than do hydrocarbons, as amorphous carbon is etched efficiently by oxygen, but the large volumes required make them prohibitively expensive.
Thin films of (K+, Na+)-β-ferrites were prepared by the partial replacement of K+ ion in K+-β-ferrite with Na+ ion to obtain a humidity sensing element having almost linear characteristic in terms of log-impedance vs. relative humidity, with humidity-sensitive characteristic controlled by changing the K+/Na+ proportion. Replacing 4mol% of K+ ion with Na+ ion yielded the thin films showing almost linear characteristic. The impedance of the film changed by more than two orders of magnitude with an increase in relative humidity. For a change in relative humidity from 43% to 80%, 95% of the total change was completed within a response time of only 10s. For the reverse change, the response time was less than 15s. These values were faster than expected. Further, the element had excellent durability in terms of humidity-sensitive characteristic. This suggests that thin films with an K:Na alkali ratio 0.96:0.04 is applicable to humidity sensors in terms of linearity in log-impedance change, magnitude of impedance change, response time and durability.
The phosphatability of low carbon, Ti-added steel sheet produced by continuous annealing was investigated. Portions of the surface of samples that had been ground were found to be inferior in phosphatability because of their excellent corrosion resistance. The addition of Mn or S, especially MnS precipitate, was effective in improving the phosphatability of the samples with the result that, in the phosphating of Ti-added and other steel sheet with superior corrosion resistance, the dissolution of Fe which is the initiating reaction, seems to have the greatest importance.
The phosphatability of the unpainted and ungalvanized surfaces of steel sheet that is coated on one side, was investigated. It was found that when unpainted surfaces were heated for 2min at 280°C, crystal size and weight of phosphate increased and the phosphophyllite ratio declined, and as a result, paint adhesion was reduced. When heated for a longer period, however, phosphatability of the surface was virtually the same as unheated surfaces. This peculiarity seems to be due to the diffusion of Mn from the bulk to the surface. Small amounts of residual Zn on the ungalvanized surfaces resulted in smaller crystals and a lower phosphophyllite ratio. Fluoride type phosphating reagent resulted in better wet adhesion than chlorate type, and the difference seems to depend on differences in the etching capacity of those two phosphate reagents.