Hard films composed of e. g. carbides, borides, nitrides and oxides exibit excellent resistance to wear, heat, oxidation and corrosion. This article describes the preparation of hard films by physical vapor deposition (PVD), chemical vapor deposition (CVD) and dynamic mixing, and presents the current status of research and development on diamond and c-BN film formation.
In activated reactive evaporation, ion plating and sputtering, in which hard films can be prepared at a high deposition rate, the particles impinging on the substrate contain a considerable amount of ions and highly energized neutral particles. Accordingly, the bias potential applied to the substrate influences the structure and properties of the deposited hard film.
CVD techniques for hard film preparation comprise both thermal and plasma. The main disadvantage of thermal CVD is the limitation on substrate materials imposed by the high deposition temperatures. Recently, plasma CVD has enabled TiC, TiN, Si₃N₄, Al₂O₃ and other hard films to be deposited at temperatures considerably lower than those used in thermal CVD.
Dynamic mixing is a method for forming hard films that combines ion implantation and vacuum deposition. TiN films prepared on Al alloy by nitrogen ion implantation and Ti vacuum deposition were characterized by a low friction coefficient and excellent wear resistance.
In terms of diamond film formation, R and D work on increasing deposition rates and expanding of the growth reagion is progressing, and experiments to develop applications are being carried out. High deposition rates have been achieved in electron assisted CVD, rf thermal plasma CVD and thermal filament CVD using organic compounds.
Finally, c-BN film deposition has been investigated using various PVD and CVD techniques. Activated reactive evaporation with a nitrogen gas activation nozzle is an effective process for preparing c-BN films.

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Strain developing polyvinyl chloride (PVC) films containing Al flake powder during formation was analyzed by a finite element method. It was found that stress in the film was concentrated at the edge of the Al flake powder, and led to breakdown of the film. Strain in rigid films was less than in flexible films. In an effort to improve the formability of PVC films containing Al flake powder used to coat sheet steel, the composition of the plasticizer in PVC plastisol was examined. It was found that by using a secondary plasticizer and a reactive plasticizer in the PVC plastisol containing Al flake powder it was possible to obtain a rigid PVC film, and the tearing load and tensile breaking load of the film were improved, resulting in good formability in a variety of roll forming processes.

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The polarization behavior of Fe-Cr-Ni ternary alloys electrodeposited on a Pt cathode from baths consisting of metal chlorides and glycine was investigated. Since hydrogen evolution predominated over metal deposition, the polarization curves were almost unchanged by metal deposition. Fe and Ni were deposited at relatively noble potentials, while Cr was deposited at the potential range of hydrogen evolution from water.

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The catalytic effect of iron, nickel, austenitic high-temperature steels and refractory materials on the pyrolytic reaction of CH₄ has been studied by thermogravimetry and gas chromatography. Metallographical observations and gas analysis indicated that refractory brick had the most significant effect on pyrolytic reaction of CH₄ because of its high porosity and because it contains a considerable amount of iron oxide which catalyzed the reaction. The catalytic effect of metal specimens was largest at the early stages, but decreased as non -catalytic products such as carbon, stable carbides and oxides occurred on the surface. Cracking and spalling of these products resulted in a local catalytic effect. The higher the concentration of iron in the high-temperature steels, the larger the catalytic effect, because iron catalyzes more actively than nickel.

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The solderability of electroless nickel-tungsten-phosphorus alloy films deposited from baths of caustic alkalin citrate (C-C) and of ammonia alkaline citrate (A-C) were studied using quantitative contact angle measurement of the solder ball.
Two kinds of solder balls, 60/40 (tin/lead), 1mm in diameter were used for solderability at 210°C. One is containing 2% resin and the other was dropped sufficent flux on it.
It was found that films deposited from the C-C baths provided improved solderability deteriorated when was dropped sufficient flux on them. In amorphous films, the greater the phosphorus content. Crystalline films with low phosphorus content deposited from A-C baths provided very good solderability with sufficient flux, but solderability was bad with solder balls containing 2% resin because of the formation of an oxide films.
The solderability of all films using solder balls containing 2% resin gradually deteriorated under heat-treatment in air at 200°C, but when sufficient flux was used there was no change whatever.

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Using CVD, tungsten coatings were deposited on iron substrates, and SiC coatings on tungsten substrates, and based on the results obtained, SiC coatings were deposited on the tungsten-coated iron.
(1) Tungsten coatings on iron. Using the reaction WCl₆(g)+3H₂(g)→W(s)+6HCl(g), tungsten coatings were deposited on iron substrates (SS41, 10×13×3mm) at 700°C under flow rates of 30mL/min of argon and 100mL/min of hydrogen. A homogeneous layer was deposited at 6g/h of WCl₆ vapor, growing to a thickness of about 20μm in 60min. The substrates were then heated at 1150°C for 30min to improve adhesion of the tungsten. The compound Fe₇W₆ was found to form between the tungsten coating and the iron substrate. The Vickers hardness of the tungsten layer was 400-500.
(2) SiC coatings on tungsten. Using CVD reaction Si(CH₃)Cl₃(g)→SiC(s)+3HCl(g), SiC coatings were deposited on tungsten substrates (10×10×0.2mm) for 30min at 1150°C under flow rates of 1.4×10^-3mol/min of Si(CH₃)Cl₃ and 100mL/min of hydrogen. The maximum thickness of the SiC layer was about 25μm. The Vickers hardness of the SiC layer was 3000-3500. The SiC layer revealed excellent resistance to corrosion in a fused salt of NaOH-KOH (50/50mol%) at 300°C. The silicon and carbon appeared to form a solid solution with tungsten at the interface.
(3) SiC coating on tungsten-coated iron. Based on the results of (1) and (2), SiC coatings were deposited on tungsten-coated iron substrates to a maximum thickness of 85μm.

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The influence of a magnetic field on the electrode reaction in the deposition of zinc were studied by the faradic impedance and rotating disk electrode techniques.
It was found that the magnetic field inhibited the deposition rate of zinc, and changed the ratedetermining step in the electrodeposition of zinc.

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