METHODS OF THE MODIFICATION OF VEGETABLE OILS IN ORDER TO OBTAIN BASE OILS

The research results were presented concerning the development of vegetable oil modification in order to obtain a base oil with desired physicochemical properties allowing the use of such oils as the base oil in pro-ecological lubricating agents. The possibilities to modify vegetable oil to obtain base oils with a higher viscosity class were presented. The process consisted of the oxidation of oils with oxygen in the presence of NHPI as a catalyst and with the use of supercritical carbon dioxide. The influence of temperature, catalyst amount, oxygen pressure, and amount of carbon dioxide in the rape-seed oil modification process were studied. As a result of vegetable oil modification, base oils with viscosity values higher than oil without modification were obtained. The significant influence of the conditions of the process carried out in a pure oxygen atmosphere and in supercritical carbon dioxide conditions was found. It was observed that it is possible to control lubricating properties of oil intended as base oil for a lubricating agent, if the process is carried out in an oxygen atmosphere and in the presence of carbon dioxide. A product with purposely changed properties in comparison with the properties of initial oil is the effect of modification.

Prepolymerization of Lacquer Sap under Pure Oxygen Atmosphere and Its Effects on the Properties of Lacquer Film

A series of lacquer saps were prepared by prepolymerization under oxygen atmosphere. The prepolymerization process was investigated by GPC, UV-Vis, FT-IR, NMR, and microscope. The results showed that the polymerization of urushiol monomer was accelerated. The content of monomer in the lacquer sap swiftly decreased from 82.68% to 47.75% in 0.5 h. The mechanism of polymerization was complex and was involved in the coupling reaction of phenyl ring, the addition reaction of the unsaturated carbon-carbon double bond groups with urushiol hydroxyl groups, and other reactions that occurred on the side chains. In addition, the prepolymerization also improved significantly the drying property of lacquer film, especially at low relative humidity. At the same time, the sizes of the water drops in the lacquer saps significantly decreased with increasing the stirring time and the surface of lacquer film became smoother, which resulted in its excellent gloss (109–125). Due to the prepolymerization, the pencil hardness and the thermal stability of lacquer film were slightly improved as well.

Study on TC4 Titanium Alloy by Laser Oxygen-Diffused Hardening Process under Different Gas Atmosphere

Surface oxygen diffusion hardening treatments of TC4 titanium alloy in Ar+O2, O2 and ambient atmosphere were performed by scanning with a pulsed Nd: YAG laser. By using different gas atmosphere with Ar+O2, O2 and ambient atmosphere, the structure and the hardness behavior of the laser oxygen hardening layers can be controlled in a wide range. Optical microscope (OM), scanning electron microscopy (SEM), energy dispersive analysis system of X-ray (EDAX) was used to reveal the microstructure and to identify the chemical composition. A Vickers microhardness tester was employed to measure the hardness distribution across both the substrate and the hardening layer. It is shown that smooth, deep and crack-free harden layers of a surface hardness ranging from 810-673Hv can be obtained under ambient atmosphere and Ar+O2 atmosphere. Cracks are observed in the sample processed under pure oxygen atmosphere. Dilution of oxygen gas with argon or nitrogen (ambient atmosphere) leads to a crack-free harden layer at the expense of a reduction in surface hardness.