Al-Cr-N films were deposited using a DC reactive sputtering apparatus under different nitrogen partial pressures of 0 to 0.303Pa. The films deposited were characterized with respect to the crystalline structure, chemical composition, hardness and wear resistance. The results are summarized as follows: 1) N content in the film increased, and Al and Cr contents in the film inversely decreased with increasing nitrogen partial pressure. N content in the film was approximately 50at%, and Al and Cr contents were each approximately 25at% at a nitrogen partial pressure above 0.089Pa. 2) The x-ray intensity of B1(200) diffraction varied with the nitrogen partial pressure and attained a maximum at 0.177Pa. 3) The structure of the films was amorphous at 0.046Pa, and changed to B1 type at a nitrogen partial pressure above 0.046Pa. 4) The hardness of the films increased with increasing nitrogen partial pressure and attained a maximum at 0.177Pa. 5) The nitrogen partial pressure during deposition affected the friction coefficient and wear resistance of the deposited films.
The possibility of cerium conversion coating has been studied as a replacement for chromate-based coating treatment on electroplated zinc on galvanized steel. The deposition of cerium (hydro)oxide film was carried out by a simple immersion into an aqueous solution of cerium(III) chloride, nitrate, sulfate, and acetate at ambient temperature. The morphorgy, composition and corrosion resistance were examined by atomic force microscope, X-ray photoelectron spectroscopy, and salt spray test, respectively. The Ce-film had a thickness up to 100nm, and had granular structure below 100nm in size. The result of salt spray test showed that Ce-film obtained from cerium sulfate solution has a higher corrosion resistance than that obtained from other cerium salts solutions. In the case of Ce sulfate solution, the sulfate anion was incorporated from immersion solution into the film. The corrosion resistance of Ce conversion coating is not improved by the morphorgy of the Ce film, but by the existence of the sulfate ion in the Ce film.
SnCl2 aqueous solution including HCl is used as a sensitizer of two-step catalyzation (sensitization-activation) pretreatment for electroless metal plating onto non-conducting substrates. The sensitizer is inactivated by aging. In this study, the relationships among the Sn2+ concentration of sensitizer, amount of adsorbates formed on the substrates, induction period of electroless Ni-P deposition and aging time have been investigated quantitatively. As the aging proceeded, the Sn2+ concentration decreased, while the amount of adsorbates, including Sn species formed by sensitization, increased. With the decrease of Sn2+ concentration, the amount of Pd adsorbates formed during activation decreased, and the induction period was extended. An independent investigation using mixture solutions of SnCl2 and SnCl4 gave similar results for aging. These results show that the aging of sensitizer induces the decrease of divalent Sn species and the rise of tetravalent Sn species, which is inactive for the formation of Pd adsorbates. Thus, the aging decreases the Pd adsorbates and extends the induction period.
Cr-Si-N coatings were prepared by incorporating several atomic percentage of Si to CrN, using an arc ion plating method. In order to change the Si content in the coatings, CrSi targets of 5, 10, 15at%Si were used. The bias voltages were changed from 0 to −250V. Silicon wafers and carburized Chromium Molybdenum Steels (SCM415) were used as the substrates. The aim of this study is to investigate the influence of Si incorporation and bias voltage on the structure and mechanical properties of the coatings. The hardness of the coatings increased drastically up to Hk4000 at 3at%Si with only a very small quantity of Si incorporated. The hardness was also influenced strongly by the bias voltage and increased with increasing bias voltage, attaining maximum at around −60V and then decreased with increasing bias voltage. This can be explained by the change of internal stress of the coatings. The adhesion of the Cr-Si-N coatings was a little smaller than that of the CrN coatings, but within a lower bias voltage range of 0˜−30V. The critical load on scratch test was 60N, the same as that of the CrN coating. The X-ray diffraction (XRD) profiles showed that the coatings with a low content of Si incorporated to CrN presented a polycrystalline structure consisting of nano-crystalline CrN which seemed to be separated from each other by an amorphous Si-N(a-Si-N) phase. It was assumed that the high hardness of the CrSiN coatings was mainly attributed to the formation of a composite structure of nc-CrN and a-Si-N and the decrease of the CrN grain size.