It has been confirmed that differences in solid solubility is important in surface hardening by MeV ion implantation. Using two substrates-Ni and Cu-which exhibit a similar crystal structure (f.c.c) and interatomic distances, the structural transformation due to MeV ion implantation was analyzed. Since carbon has slight solid solubility to Ni but not to Cu, 3MeV carbon implantation of the substrates was carried out at doses of 1×1016-5×1017ions/cm2. The hardness depth profile in the implant layer was estimated by a dynamic micro hardness tester. Microstructure produced by implantation was obserbed by microscope. The crystal structures were investigated by XRD. AES and SIMS were also performed to obtain the profile of the implantated carbon. Remarkable differences between Ni and Cu are found in terms of hardness profiles, implantation ion distribution, and crystal structure transformation. With Ni, maxium hardness with Gaussian profile occurred at a dose of 3×1016ions/cm2, and it is considered that internal stress is the major facter in hardening up to this dose range. At doses above 1×1017ions/cm2, recrystalization may cause a broadening of the hardening profile, and the production of carbide compounds is thought to be the cause of the hardening. In the case of Cu, the hardness distribution becomes scattered with increases in dose. It is thought that this is due to the fact that the implanted carbon gradually precipitated because carbon has no solid solubility in Cu.
Aluminum thin films were prepared by vacuum evaporation and ion plating on SPCC substrates, and their crystal orientation and morphology were investigated by X-ray diffraction and scanning electron microscopy. The influences of argon gas pressure and bias voltage were also estimated by applying the adsorption inhibitor theory and the sputter theory. Deposition rate, ionization voltage and substrate temperature are also known to influence the orientation and the morphology of aluminum films, but these factors were kept constant in this study The relative intensity of the high surface energy plane (200) increased at an argon gas pressure of 7.3×10-3Pa, while that of the low surface energy plane (111) was increased by the effect of argon gas sputtering Surface crystal grain size decreased with increasing the argon gas pressure at constant bias voltage. In cross section, the morphology exhibits a columnar structure at high bias voltage, but at low bias voltage it exhibits a fine granular structure due to the adsorption of argon gas. A reciprocal relation between orientation and morphology was demonstrated for aluminum films deposited by ion plating.
Tribological properties of Pb-Sn-Cu films prepared by DC magnetron sputtering have been studied using a friction and wear tester. It was found that the tribological properties were influenced by the argon gas pressure during sputtering, the Sn grain size, and the Cu content of the films. The friction coefficient of the films decreased with increasing argon gas pressure, and wear resistance improved. The friction coefficient of the films also decreased with finer Sn grain size, and wear resistance improved with increased Cu content.
Composite coatings codeposited with PTFE particles into an electroless nickel matrix were prepared and their friction and wear characteristics were studied. The hardness of the coatings decreased with increasing PTFE content. Friction tests showed that the higher the PTFE content, the lower the coefficient of friction remained even after prolonged sliding motion and the coefficient of friction of the coatings remained low even increased the sliding speed. The relationship between vertical load and friction resistance was linearly proportional, satisfying Amontons' law, except at light loads. The coatings tested were found to have good self-lubricating properties and wear characteristics.
Electroless deposition of bismuth has been achieved, probably for the first time, using stannous chloride as a reducing agent. Bismuth films were autocatalytically deposited on aluminum substrate activated with palladium at a rate of 1.84mg·cm-2·h-1. Optimum bath composition were 0.08M, 0.34M, 0.20M, 0.08M and 0.04M for bismuth trichloride, trisodium citrate, NTA, disodium EDTA and stannous chloride, respectively. Rapid film deposition was obtained at pH8.8 and 60°C. The films were grown to the desired thickness by renewing the plating bath every 30 minutes. It was observed from X-ray analysis and X-ray fluorescence spectrometry that the crystal structure of deposited film was not affected by the plating conditions, and that it contained no trace of tin. UV absorption spectra of the plating bath showed that the EDTA formed complex salts with Bi3+, Sn2+, and Sn4+, while the citric acid and NTA served as solvents for the insoluble complex salts formed by EDTA with Sn2+ and Sn4+.
A method of flash anodizing aluminum in acid baths with a momentary high current was investigated, with a view to suppressing increases in bath temperature and reduce electoricitiy consumption by passing a high current at regular intervals in a non electrolytic state. The acid baths used were (COOH)2·2H2O, H2SO4, H3PO4, CrO3 and current density were 4∼55A/dm2 and anodizing time was 30min. It was found that changes in bath temperature were the same as or less than with the standard method. In phosphoric acid, there was noincrease in coating thickness, but the thickness obtained in the other baths was about double the standard. Hardness of the coating obtained by the two methods were about similer. The effect of this method in controling bath temperature increases and in increasing of coating thickness marked using oxalic acid bath.
Bath compositions suitable for the anodizing of aluminum were investigated in organic alkaline baths (hydrazinefluoride base) with additions of ammonium fluoride and organic acid salts In baths containing organic acid salts (CH3COONH4, (NH4)2C2O4, (NH4)2C4H4O6 or (NH4)3C6H5O7), uniform films were formed but in baths without these additives the films were not uniform The films that were thickest (about 15μm) and hardest (about 23 as Marten's scratch hardness under load of 50gf) were obtained in a 0.1mol/L hydrazine bath containing 0.1mol/L ammonium fluoride and 0.05mol/L ammonium citrate by anodizing for 30min at 20°C with a constant current density of 2A/dm2 SEM observation of the film surface showed that the films formed in baths containing ammonium oxalate or ammonium citrate had larger pores (500∼1000Å) than those formed in baths containing ammonium acetate or ammonium tartrate. It is concluded that the formation of large pores is caused by the dissolution of cell walls at higher voltages (about 110V)
The feasibility of using an electric resistance wire strain gauge on the reverse side of metal substrates, to detect the influence of the substrate metal on the average strain in the deposit obtained from a conventional chromium plating bath and on the average strain in substrates deformed by hydrogen codeposition and absorption in a sulfuric acid solution was studied. The following results were obtained. (1) The strain gauge on the substrate was highly sensitive to slight strain deformation of the substrate during electrolysis. (2) The larger the amount of hydrogen absorbed by a substrate, the greater its compressive strain deformation in the early stage of electroplating. In this study, the compressive strain deformation of substrates was in the order of Ti>Fe>Ni>SUS>Ni-P alloy, as was the capacity to absorb hydrogen. (3) Titanium substrates having the greatest compressive strain deformation due to hydrogen absorption showed very poor adhesion to chromium films deposited on them.
The mechanism by which organic reagents prolong the induction period of the reaction between 1, 1, 1-trichloroethane (CCl3CH3) and aluminum (Al) was investigated in terms of changes in electrical conductivity. Organic reagents were first added in various concentrations to a CCl3CH3 solution containing AlCl3, which had high electrical conductivity due to the formation of the complex compound CCl2CH3+[AlCl4]-, and the electrical conductivity of the solution and the induction period of the reaction between the solution and Al were then measured. The results are summarized as follows: 1) Organic reagents such as amines, which markedly lower the electrical conductivity of the solution, had a strong retarding action on the reaction and were found to become a powerful inhibitor. Even after the dissolution of Al had set in, the addition of amines to the solution could inhibit it. 2) Alcohols and ethers had not a very great effect on the retarding action. This may be attributed to the fact that they failed to effect a significant decrease in electrical conductivity, or, when added in excessive amounts, even increased it. Alcohols and ethers could not inhibit the dissolution of Al once it had set in.
The effect of pH on the pitting corrosion of copper in an open cooling system containing an inhibitor such as nitrilotris methylene triphosphonic acid (ATMP), benzotriazole (BTA) or zinc sulfate (ZnSO4) in the cooling water has been investigated by immersion test and electrochemical measurement. It was found that pitting corrosion tended not to occur, when pH rose from 3 to 7. A close relationship was found between the electrochemical properties (Ecorr (corrosion potential)/Eb (breakdown potential)) and the occurrence of pitting corrosion in copper such that when Eb≥ECORR pitting did not occur.
After nickel plating on steel substrates and tin plating on top of that, heat-treatment at 180°C was applied for 72 hours to form tin-nickel alloy films X-ray diffraction measurement of these films revealed the formation of Ni3Sn4, Ni3Sn2 and Ni3Sn The tin-nickel films were superior in corrosion resistance to the decorative nickel-chromium plating ordinarily used