It is considered important to verify that the findings previously obtained in a fundamental study involving mechanical plating of Z-iron (an Fe-Zn system alloy containing iron nuclei) carried out using a laboratory gas ejector also apply to the operation using a commercial rotor ejector. The principal parameters studied were: (1) the effect of feed amount on deposit density: (2) the effect of repeated ejection on deposit density: and (3) the deterioration of the Z-iron with repeated use. Mechanical plating of steel bolts with ZZ-48H, the thermally-treated powder of ZZ-48, was also done to verify its superiority over ZZ-48. The study demonstrated that the basic knowledge obtained in the fundamental study is essentially applicable to commercial-scale operation. It is found that ZZ-48H is an efficient ejection powder, yielding a higher deposit density and longer life than ZZ-48.
Electroless plating baths for NiCr alloy film deposition were investigated. The baths contain Cr-complex, which is obtained in the reduction of chromium (VI) oxide with citric acid. Higher concentrations of reductant than in the case of conventional electroless Ni baths are used in the bath; dimethylamineborane for the NiCrB bath and sodium hypophosphite for the NiCrP bath, respectively. The NiCrB film plated from the bath contains up to 1.7 at. % of codeposited Cr. Although virtually no Cr was codeposited from the NiCrP bath, it was possible to obtain NiCrP films with 1.0 at. % Cr codeposited by using electrolysis in combination. Despite the low Cr content, the specific resistance of the NiCrB and NiCrP films showed the heat-dependence behavior that differed markedly from that of conventional electroless Ni alloy films. The above behavior suggests the effect of Cr codeposition.
NiAl was deposited by reduced pressure CVD to form hot corrosion resistant coatings for the cooling pessages of heavy duty gas turbine buckets. AlCl3 and AlCl were used as chemical reaction gases with H2 gas as carrier gas. An NiAl coating layer was formed by deposition and subsequent diffusion of Al into Ni base superalloy. Optimum coating conditions were surveyed to obtain a uniform coating thickness for the complex shaped cooling passage utilizing a simulation model. It was found that in the model bucket cooling passage the ratio of NiAl layer thickness at the outlet to that at the inlet was about 45% under coating conditions of 950-1000°C and 20-40Torr and using a reverse flow prevention device.
Implantation to a pure chromium substrate of (N2++N+) ions at an ion beam energy of 90keV and of N2+ ion at beam energies of 500keV and 1MeV were followed by investigation of the depth distribution of nitrogen by Rutherford backscattering spectrometry (RBS). The process of redistribution by heat treatment also studied. Depth distribution results revealed that RBS is effective for analyses based on the total amount of ion implantation of gaseous elements such as nitrogen. The nitrogen distribution resulting from implantation carried out at high dose also showed a Gaussian shape. The nitrogen distribution obtained from low-energy ion implantation was coincident with the results of a simulation using the LSS theory. Excess implanted ion did not form chromium nitrides, but remained unreacted as nitrogen gas and formed blisters. Nitrogen heat treated at 1073K for 1h in vacuum changed to trapezoidal distribution. It was confirmed that the upper limit concentration was dependent on the Cr2N phase and redistribution occurred to maintain its phase. This redistribution was interpreted in terms of the nitriding of the whole implanted layer, as a result of a process particle growth with the Cr2N particles as nuclei.
This experiment was carried out with the aim of depositing composite films of Ti (C, N) by a reactive ion plating method. First, appropriate conditions for the depositing of TiN film were found and C2H2 gas was mixed with N2 gas under the same conditions in an attempt to synthesize composite Ti (C, N) films. Even when C2H2 gas content was increased to 50%, there was little solution of carbon atoms into the TiN phase. An attempt was then made to synthesize composite Ti (C, N) films by mixing N2 gas with C2H2 gas under conditions appropriate for the depositing of TiC films. It was found that the single phase of the solid solution film of Ti (C, N) was synthesized despite the increase in the ratio of N2 gas, and that the color of the film became yellowish owing to the substitution between carbon and nitrogen atoms.
The corrosion protective properties of electroless Co-Ni-P alloy plating were examined in 5% NaCl solution. The corrosion resistance of Co-P film was better than that of Ni-P film. The corrosion potential of the films was less noble in the order Ni-P, Co-P, Co-Ni-P, and contact corrosion current density in circuits constructed of deposited film and an Fe plate decreased in the same order. Thus the amount of dissolution of Fe substrate in the corrosive solution decreased and the corrosion protective properties of the depositions on the Fe substrates improved in the same order.
This study relates to preparation conditions and physical properties of electroplated amorphous ternary Ni-Co-B alloy films that were prepared by the authors based on their previous studies of electroplated binary Ni-B alloy films. The results can be summarized as follows: 1. Preparation of amorphous Ni-Co-B alloy films by electroplating is possible if trimethylamineborane is used as an additive. 2. Increases in depostied cobalt reduce codeposited boron and produce amorphous films, when the deposited cobalt content is approximately 4wt.% or less, and when boron codeposition is approximately 5wt.%. 3. The maximum hardness of heat treated amorphous Ni-Co-B alloy films was Hv (0.025) 1250 at approximately 400°C, while that of heat treated amorphous Ni-B alloy films was approximately Hv (0.025) 1030 at approximately 300°C. 4. Thermal analyses of various Ni-B and Ni-Co-B alloy films, including amorphous films, by differential scanning calorimetry showed that every alloy has its calorific power, which increased with codeposited boron; the calorific power/deposited boron relation for Ni-B alloy films was linear and that for Ni-Co-B alloy films was inversely parabolic. Every curve showed a discontinuity at a codeposited boron content of approximately 4.5wt.%.
The effect of the crystal structure of various nickel substrates on the orientation of plated gold films was studied. The gold plating was conducted in a solution primarily composed of gold potassium cyanide at 338K and pH=6.5 with a current density of 5mA/cm2. It was found that the crystal structure of the nickel substrate influenced the orientation of the gold film as follows: (i) for films thinner than 0.2μm, there was epitaxial growth of gold film on the nickel substrate as (111)Au||(111)Ni, (200)Au||(200)Ni and (220)Au||(220)Ni: (ii) for films between 0.2 and 3μm, there was growth of the (110) plane of gold on the nickel substrates; and (iii) for films thicker than 3μm, the growth plane orientations were (111)>(220)>(200), which is considered the characteristics of gold plating under these condition.
In response to the increasing demand for improved corrosion resistance on steel parts of automobiles and aircraft, plating with Zn-based alloys is being applied in place of pure Zn plating. The effects of Co content and deposited phase on the corrosion resistance of Zn-Co alloy electrodeposited under various conditions from sulfate solutions on iron substrate specimens have been investigated by ICP, X-ray diffraction analysis, EPMA, and salt spray tests. X-ray diffraction analysis revealed that Zn-Co alloy electrodeposits having a Co content of 10∼20wt.% were γ-phase (Co5Zn21), those having a lower Co content were dual (η+γ) phase, and that those having a higher Co content were dual (α+γ) phase. In salt spray tests, γ-phase deposits of 10∼20wt.% Co content showed the best corrosion resistance. The corrosion product layer consisted only of ZnCl2·4Zn(OH)2 which has low electrical conductivity. It is suggested that this corrosion resistance is attributable to the effects of the γ-phase and corrosion product.
At pH 7, the occlusion of hydrogen in the alloy deposits decreased markedly compared to that in single deposits of palladium. Smooth, bright deposits could be obtained over a potential range of -0.7 to -1.1V vs Ag/AgCl. The palladium content of the alloy deposits increased with [en]/[M] ratio, whereas current efficiency decreased with increases in the potential and the ratio. When the [en]/[M] ratio exceeded 3 at pH 9, current efficiency decreased markedly due to the decrease in the deposition rate of nickel and the acceleration of hydrogen deposition. Palladium content showed its maximum value of 94% at a ratio of 3, and decreased at higher ratios. Smooth deposits could be obtained even at potentials as low as -1.1V from baths having a high [en]/[M] ratio at a pH above 8. This suggests that ethylenediamine acts not only as a complexing agent but also as a leveling agent.