Oligomer formation reactions during the preliminary treatment of a solution system consisting of ATMS-EtOH-H2O, and the hydrophobic treatment of TiO2, Ti-Fe-Al composite oxide and α-Fe2O3, which have different numbers of surface OH groups, using various preliminarily treated alkyltrimethoxysilane (ATMS) solutions, were investigated. The main findings were as follows: (1) The maximum M value, which is a parameter of the hydrophobic degree, for the metal oxides investigated showed a tendency to increase with the increase in the carbon number of the alkyl groups composing ATMS. The maximum M values of Ti-Fe-Al composite oxide and TiO2 appeared to be almost the same, whereas those of α-Fe2O3 were 10~20% smaller. The M values obtained with i-BTMS were lower than those with n-BTMS, despite the identities of the oxide tested. (2) There is an intimate relationship between the oligomer states in preliminarily treated solution and the maximum M values obtained for all metal oxides tested. (3) Although the hydrophobic treatment was performed using a theoretical amount of preliminarily treated ATMS, the maximum M values for all metal oxides tested increased with the increase in the number of OH groups on the substrate surface.
A preparation of hydrophobic metal oxide powders including TiO2, Ti-Fe-Al composite oxide and α-Fe2O3, using n-BTMS-EtOH-H2O with a mixing mass ratio of 10 : 6.8 : 3.2, was investigated in the pH range of 3.0 to 9.0 using CH3COOH and NH4OH. The main findings obtained were as follows : (1) The hydrophobic degree of metal oxides is enhanced when the hydrolysis reaction of n-BTMS proceeds quickly and successive condensation is rather slow. (2) In the plot of the average molecular weight of n-BTMS oligomer versus duration time on a log-log scale, no induction period followed by a slow increase in molecular weight was detected at pH 3.0, while at other pHs the induction period was followed by a linear increasing stage. The induction period was followed by the pH order 3.3<4.0<9.0<5.3 (de-ionized water exposed to air), and the slope of the linear portion increased in the pH order 3.3<4.0<9.0<5.3. (3) The maximum M value, which is a parameter of the hydrophobic degree, obtained for Ti-Fe-Al composite oxide was 65% at pH 3.0, 3.3 and 4.0, while that for TiO2 was 60% at other pHs, except at pH 4.0 and with de-ionized water. The maximum M value determined with α-Fe2O3 was only 40% at the pHs of 3.0 and 3.3. (4) To provide the maximum values of M for TiO2 and Ti-Fe-Al composite oxide, dimers to tetramers were required, whereas a polymerization degree above 2.5 was necessary for α-Fe2O3.
Nitrogen-containing stainless steel coatings were synthesized from different stainless steel targets (SUS 304, 310 S) by a cathodic arc-ion plating process, using two types of arc-cathode, namely, conventional and magnetically filtered cathodes. The effects of the cathode type, target material and process parameter on the structural, compositional and mechanical properties of coatings were investigated. From X-ray diffraction analysis, coatings deposited by a magnetically filtered cathode showed a new crystal structure, which could be identified as a cubic type zinc-blend or rock-salt structure, whereas the coating deposited by the conventional cathode was a mixture of nitrogen supersaturated fct (face centered tetragonal) type gamma Fe-N phase and Fe3N. The relationship between nitrogen partial pressure (PN2) and nitrogen content in the coating showed quite different behavior depending on the cathode type used. For the conventional cathode, the nitrogen content increased gradually as the PN2 increased from 0.8 to 2.7 Pa and reached approximately 30mol% at the highest PN2. However, using a magnetically filtered cathode, the nitrogen content was about 40 to 50 mol%, at a pressure range of 0.7 to 1.0 Pa. The change in the crystal structure, depending on the cathode type, was considered to be primarily due to the difference of the nitrogen content in the coatings. It was concluded that using the magnetically filtered cathode, ionization of the gaseous species in the process chamber could be enhanced due to the longer electron path from the cathode to the anode, resulting in enhanced reactivity of nitrogen with metallic elements.
It is known that an anodic oxide film on aluminum shows a weak electroluminescence (EL) characteristic during anodization in a sulfuric acid solution or in an oxalic acid solution. Anodic alumina films doped with Mn or Tb show a strong yellow or green EL, respectively. Next, the application of ion doped alumina films to a solid-state EL device with rare earth (RE) supported by the barrier type anodic alumina films was investigated, because anodic alumina films implanted with RE show continuous and uniform luminescence. The rare earth metals are implanted into the barrier type anodic aluminum oxide film by an ion accelerator. The red luminescence of Eu3+ can especially be confirmed if Eu+ was implanted. The influence of the crystalline structures of Eu+ implanted alumina on the emission intensity was investigated. Three kinds of structures α, γ and γ'-alumina were selectively produced by adjusting process parameters at the anodization of aluminum. As a result, the specimen of γ'-alumina showed the strongest EL intensity among them. It can be expected that a higher intensity and longer life EL device will be obtained by the combination of γ'-alumina films and ion implanted RE metals.
Electrolyzed acid water obtained by the electrolysis of a dilute NaCl solution in the anode compartment shows low pH (acidity) and high ORP (Oxidation Reduction Potential), and it acts as an acid solution. By utilizing the electrolyzed acid water, metal and lead frames with oil were washed and cleaned, and then the cleanness of metal and lead frames for electronic products was evaluated. The surface analysis and quantitative data on the remaining residual oils and ionic contamination, AES (Auger Electron Spectroscopy) analysis on metals, and wire-bond pull strength of the lead frames which were washed and cleaned by the electrolyzed acid water, showed a higher level of cleanness compared to the that of the conventional cleaning method. The efficiency of degreasing and cleaning by electrolyzed acid water is supposed to be due to its high dissolved oxygen concentration and an operation of dissolving metal oxides and oils.
The wettability of molten polymer on stainless steel and coatings was evaluated, for the purpose of improvement of spinnerets for synthetic fibers. The three types of molten polymer (Polypropylene : PP, Nylon-6 : NY-6, Polyethylene Terephthalate : PET) are pushed out upward vertically from a small hole of SUS316 disc by means of a cylinder-piston. The shape of the molten polymer is detected by a CCD camera, and the contact angle values were evaluated. As a result, it was found that, after molten polymers were pushed out for 300 sec., the contact angles provided good reproducibility, with the coefficient of variance of the measurements being about 4%. The contact angles of molten polymer on PVD coatings (Cr-N, Ti-N, Ti-C, Si-C) were in the sequence of Cr-N>SUS316>Ti-N, Ti-C, Si-C for PP at 220ºC, Cr-N>>SUS316, Ti-C, Si-C>Ti-N for NY-6 at 250ºC, Si-C, Ti-N>>Ti-C, Cr-N>>SUS316 for PET at 285ºC. As a result of XPS measurements, it was suggested that the contact angle of molten PET at 285ºC was influenced by the hydroxyl on the surface on the specimen.
The role of functional groups on graphite edge during Cu/graphite composite plating was investigated by potentiometric titration method. It was clarified that the reaction between edge functional groups and Cu2+ ion depends on the pH of the plating solution. The surface morphology of the electrodeposited film indicated that the structurized Cu/graphite film can be fabricated by controlling solution pH.