The effects of high energy ion-implantation treatment on the mechanical properties of diamond-like carbon (DLC) films have been investigated in this study. The micro-tribological properties of DLC films formed by using various methods such as ion-beam enhanced deposition (IBED) and plasma based ion-implantation (PBII) have been examined by means of atomic force microscopy (AFM) and acoustic emission (AE) oscillation scratch tester. With the PBII method DLC films were deposited on silicon wafer under conditions of a pulse bias of −5 to −20kV in an atmosphere of CH₄ plasma. DLC films were deposited with the IBED Method by means of ion-plating and the deposition was performed using the methods of dynamic mixing and static mixing at an acceleration voltage of 120kV. These main results of above-mentioned tests are summarized as follows.
(1) In case of DLC films deposited by the PBII method, there is an existing peak voltage at which the maximum hardness and durability were provided.
(2) DLC films deposited with PBII method shows higher hardness than these deposited with the IBED method does but they also have brittleness is large. Therefore, the quantity of micro wear of DLC films with PBII was larger than that of DLC films with IBED.
(3) The critical load of PBII-DLC films increased with an increase on a peak voltage. And, the adhesive strength of ion beam mixing DLC films deposited at 120kV is similar to that of PBII films deposited at a peak voltage of several tens of kV.

View full abstract

Al-Cr-N films were deposited by a DC reactive sputtering method using three targets of 75at%Al25at%Cr, 50at%Al50at%Cr and 25at%Al75at%Cr disks. The Al-Cr-N films were characterized with respect to the chemical composition, crystal structure by XRD, GDS, TG-DTA, FE-SEM and TEM. The high temperature oxidation behavior of the films was investigated by heating at 1000^ºC in air. The results were summarized as follows :
(1) The Al-Cr-N films were not severely oxidized at temperatures under 1200^ºC. The oxidation resistance of the Al-Cr-N films was improved by more than 200 degrees compared with that of the Ti-Al-N film.
(2) Al_0.75Cr_0.25N film formed crystallized Al₂O₃ on the surface after heating at 1000^ºC for 120min in air. Al_0.5Cr_0.5N and Al_0.25Cr_0.75N films formed two-phase mixtures of crystallized Al₂O₃ and Cr₂O₃.
(3) The protective layer composed of Al and Cr oxides was formed on the top surface of Al-Cr-N films during the high-temperature oxidation test. The oxidation resistance of Al_0.25Cr_0.75N film is the lowest among the Al-Cr-N films.
(4) The fractured cross section of Al_0.5Cr_0.5N film showed columnar structure before oxidation, and changed to granular structure after heating test at 1000^ºC.

View full abstract

Various plasma polymerized organic acid thin films were obtained by using acrylic acid, p-toluenesulfonic acid or phthalic anhydride as an organic acid raw materials monomer, and their chemical structures and functionalities were investigated. Functional groups of organic compounds tend to be destroyed with increase of the plasma power output. There are two methods for the addition of various functionalities to material surfaces as follows : One is due to the residual functional groups derived from organic acid monomer in plasma polymerized thin films, and the other is the novel formation of functional groups by chemical reactions during plasma. As for the acrylic acid and p-toluenesulfonic acid, the decomposition of the hydrophilic functional groups such as carboxylic acid (R-COOH) or sulfonic acid (R-SO₃H) resulted in influencing to their surface electric conductivity properties, because the amount of residual hydrophilic groups had an effect on the electrical characteristics of the thin film surface. The water wettability and adhesive properties of the plasma polymerized acrylic acid thin film changed due to the varieties of their chemical structures over the surface of the thin films. Plasma polymerized p-toluenesulfonic acid thin film showed the better response to the change of electrical conductivity on the thin film surface for the humidity.

View full abstract

A SUS316 substrate surface was modified with fluoroalkylsilane (FAS) by a chemical vapor reaction with the aim to form fluoride thin layers on the metal surface. The water repellency of the substrate surface increased with the reaction time. When the reaction temperature was 150^ºC and the reaction time was over 1 hour, the water contact angle of the substrate surface reached 110^º. Furthermore, a random multi layer formed when the reaction time increased and the reaction temperature was raised. The increasing the amount of FAS in the reaction stage reinforced the durability of this layer. And the layer that formed on the SUS316 substrate was stronger than that which formed on the glass. X-ray photoelectron spectra (XPS) analysis revealed C-F covalent bonds on the treated substrate. On the basis of these results, the formation mechanism of fluoride thin layers was discussed.

View full abstract