Polymerized organosilicon films containing fluorine were fabricated using microwave plasma-enhanced chemical vapor deposition (MW PECVD). Chemical and physical surface properties were controlled by changing PECVD reaction conditions. Water-repellent films having water contact angles exceeding 150 degrees were obtained at Ts=70°C and total pressure exceeding 40Pa. Films were prepared from a mixed source gas of tetramethylsilane (TMS) or hexamethyldisilane (HMDS), containing no oxygen atoms, and a (heptadecafluoro-1, 1, 2, 2, tetrahydro-decyl)-1-trimethoxysilane (FAS-17). FAS-17 was introduced into a reactor using Ar carrier gas. Water contact angles of these films increased from 115 to 160 degrees as total pressure increased from 25 to 50Pa. Their surface roughnesses increased from Rrms=11.3 to 60.8nm. The film structure became more granular when prepared at a higher pressure. With an increase in the substrate temperature, however, film surfaces became smooth and perfluoro-alkyl groups peeled from films, markedly decreasing in water-contact angles. Films were then prepared from hexamethyldisiloxane (HMDSO), which contains oxygen atoms, and FAS-17 with Ar. Rrms ranged from 10 to 12nm and contact angles remained constant at 110 degrees in the total 25∼50Pa. Oxygen atoms in the source material, i. e., HMDSO, promoted film surface smoothing and reduced water repellency.
The car air conditioner evaporator is an aluminum heat exchanger that cools the air in an automobile. About 20 years ago, evaporators were treated only with chromate to prevent corrosion. Since the early 1980s, there has been increasing demand for hydrophilic properties for compact, highly efficient evaporators with narrow fin spacing and greater air flow to prevent increasing air pressure from dropping. In addition, the need has grown for greater demand for more comfortable air with fewer smells. A variety of odors emanate from air conditioners. This report describes “rotten” odors, -mustiness, socks, etc.-caused by microorganism propagation, and methods to reduce odors by forming a hydrophilic treatment including a biocide. Culture and smell evaluation results suggest that the rotten odor caused by bacteria is stronger and more uncomfortable than that caused by fungi. We developed a way to prevent oder by surface treatment that provides the evaporator surface with hydrophilic properties and bacterial resistance.
Thermal-spray WC cermet coatings corrosion by high velocity oxygen-fuel spraying was studied using potentiodynamic and potentiostatic polarization in an aerated sodium sulfate solution. The cermet coating was the WC-Co, WC-Co-Cr, and WC-Cr-Ni matrials on the carbon steel substrate. The anodic polarization curves of WC cermet coating were passive, transpassive, and reqired oxygen evolution. Cathodic polarization curves show a limited diffusion current of oxygen and hydrogen evolution. Coatings tended to decrease passive current density with increasing pH of solution. The presence of Cr in the matrix alloy decreases passive current and controll the dissolution of WC and Co. The Ni-Cr alloy matrix without Co showed no dissolved WC.
Ferromagnetic Co-based metals were electroless-deposited into microstructured porous silicon (PS) pores. Perpendicular magnetic anisotropy changed in the electroless Co-B layer. Stronger layer anisotropy was obtained using a self-supporting PS as a substrate. Microstructure and magnetic properties of the metal layer were observed through a field emission scanning electron microscope (FE-SEM) and a vibrating sample magnetometer (VSM). Anisotropy was found due to the structure of the deposited layer. Higher coercivity of perpendicular magnetization curves was obtained in an electroless Co-Mn-P layer. This indicates the potential for applying this composite material to the perpendicular magnetic recording media.
In response to growing needs for improved corrosion resistance in the steel parts of automobiles and aircraft, plating with Zn-based alloys is being applied in place of pure Zn plating. Zn-based composite plating is also expected to exhibit better corrosion resistance than pure Zn or Zn-alloy plating due to the existence of dispersed particles. Experiments were undertaken to determine the dependence of Zn-Co-SiO2 composite plating electrodeposition and surface morphology from sulfate solutions on surfactants. We found that the SiO2 content of deposits without surfactants increased with SiO2 concentration in the bath, but not for those with surfactants. The SiO2 content depended on the SiO2 concentration and the cathode current density. Despite identical plating conditions, surfactant addition is lowered the deposit's Co content and greatly affected the crystal structure and surface morphology.