Advanced Materials Research Vols. 287-290

Abstract: In order to increase the service life for piston rings, the (Cr ,Ti) N composite coatings have been successfully synthesized on 65Mn steel substrates by using arc ion plating technology. The influences of Ti content on the deposition velocity, phase structure , surface morphology and hardness of the composite films were investigated. The results showed that the surface roughness will reduce after addition of Ti element. And the hardness, residual stress of CrN films will increase after addition of Ti element. The preferential growth orientation of the composite film changes from CrN (111) to CrN (220). With increasing Ti content, the phase structure of CrTiN films will change from CrN type to TiN type. When the Ti atomic number was 0.62, the hardness of CrTiN composite films reaches the maximum, about 35GPa. Wear test indicate that the fiction of CrTiN films are lower and the wear volume are less than CrN films. The CrTiN composite films performs better than binary CrN films in teams of hardness and wear resistance at high temperature.

Abstract: ZnS films were prepared by radio-frequency (RF) magnetron sputtering method. The effects of substrate temperature and annealing treatment on the properties of ZnS films were studied. The ZnS films were characterized by X-ray diffraction (XRD), UV-visible spectrophotometer, and electrical measurements. The results showed that the higher substrate temperature and post-deposition annealing treatment was helpful in improving the crystalline quality of the films, and the film had an n-type conductivity. N-type ZnS films were also deposited on p-type single-crystalline silicon (Si) substrates to fabricate ZnS/ Si heterojunction. The current-voltage (I-V) characteristic of the heterojunction was examined, which showed a rectifying behavior with turn-on voltage of about 2V.

Abstract: The Soil-Structure Interaction (SSI) Effect exists everywhere, but the existing researches on actual damping of SSI system are not so sufficient, and the analysis of its real dynamic response becomes unsuitable to engineering applications. In this paper, the possibility of regarding SSI system as classical damping system in linear elastic range is studied. The motion domains and the equation of the dynamic system in each domain are confirmed with respect to boundaries. The research on Shaking Table Test of SSI system is shown as an example of supporting the feasibility of regarding SSI system as classical damping system similarly.

Abstract: Boron carbon nitride (BCN) is a new type of super-hard material with excellent properties, and is very suitable for use as a wear-resistant protective coating and solid lubricant. In this report, we prepared BCN films on YG8 cemented carbide substrate by magnetron sputtering. The structure and composition of the films were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The adhesiveness of the films was studied by scratch test. Results from these analyses show that BCN films deposited on the YG8 substrate has good adhesion properties. We also demonstrated that target power and substrate bias have a great impact on the adhesiveness of the films, and reasonable process parameters can improve the adhesiveness of the films.

Abstract: Undercut is one of the most important problems which restrict welding speed. The research indicated that surface flow direction of welding pool near the periphery is the most important reason of undercut occurred. When the existence of surface active element (e.g. the content of S is about 0.02-0.04% in steel) change the sign of surface tension temperature coefficient to positive, undercut always occurs in TIG moveless welding, and not occurs when the content of S in iron is very low( e.g. S% is less 0.01%). Temperature gradient is the most important factor which influences the depth of undercut. The depth of undercut is bigger with the increase of temperature gradient when the other parameters are the same. When filling metal into welding pool, it restrained the molten metal movement from periphery to the pool center. So it can reduce the tendency of undercut, and eliminate undercut as increasing of filling metal ultimately.

Abstract: The ultrafiltration membrane technology which has been regarded as the water treatment technology for the human beings in the 21 century develops on the basis of reverse osmosis. The main function of the ultrafiltration membrane technology is to clear liquid, to reject solute concentration and solute fractionation, which can dislodge biological molecules, polymers and colloidal substances. The study introduces the situation of ultrafiltration membrane in treating drinking water in the fundament of the experiment of ultrafiltration membrane technology in Shiyuan water treatment plant in Zhengzhou,China.

Abstract: The anisotropy of tensile properties and charpy impact fracture toughness and its relationship with UOE pipe forming has been study on X80 micro alloy steel. All samples selected from 90^º and 180^º of pipes in transverse and longitudinal orientations after UOE forming. The steel was supplied as a hot rolled plate with accelerated cooling. Microstructure of the micro alloy steel was various combinations of acicular ferrite, granular ferrite and M/A phases. Charpy impact fracture toughness tests were carried out in -50 °C to 0 °C. Minimum and maximum yield strength appears in the 180^º and 90^º of pipe in longitudinal and transverse orientations respectively. Increasing in the yield strength related to minimum amount was about 5.8 % after UOE forming. Comparison between yield strength after and before forming appears increased about 6.9 % due to forming. With decreasing in the test temperature from -50 °C to 0 °C, fracture energy decrease up to 0.9 % that it’s very little and relinquishment. However for samples that fractured in the temperature of -50 °C difference between highest and lowest energy was about 5.9 %. Charpy test results appear that fine M/A phase not a major factor on decrease of upper shelf energy, if homogenize distributed in the acicular ferrite matrix.

Abstract: HfO₂ thin films were prepared by radio frequency (RF) magnetron sputtering at different RF powers. The influence of RF power on optical properties of HfO₂ thin films were investigated by spectroscopic ellipsometry (SE) toghther with high-resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared spectroscopy (FTIR). The results show that there is a SiO₂ interface layer between HfO₂ thin film and Si substrate. A four layer structured model consisting of SiO₂ interfacial layer was used to fit the SE data. With the increasing RF power, the refractive index of the HfO₂ thin films increases firstly and then decreases and, the extinction coefficient of the HfO₂ thin films increases little.

Abstract: Three layers polyethylene (3PE) anti-corrosion coating was widely used in oil or gas transmission pipelines in the world. Special HDPE (SHDPE) was used in the outer layer of 3PE coating, which is very important to the performance of the whole coating system. However, till to now fewer study about SHDPE crystallization have been reported. In this paper, the crystallization characteristic of SHDPE and 3PE coating were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), modulated differential scanning calorimetry (MDSC). The results showed that, the crystallinity and lamella thickness of SHDPE were decreased with the increase of cooling rate in fabrication process. Middle adhesion layer of 3PE coating accelerated nucleation and improved the crystallinity of the near zone PE layer. The skin region of 3PE coating had lowest crystallinity due to the highest cooling rate, and the crystallinity was increased from skin to core region of 3PE coating.

Abstract: The laser welding of Aluminum-Lithium alloy (Al-Li) alloy were conducted to investigate the weld porosity features in this paper. The results show that there are two kinds of weld porosity existing for laser welding Aluminum-Lithium alloy sheet. They are can be divided into metallurgical porosity and unstable keyhole porosity according to their different reason causing them. The mechanism of unstable keyhole porosity occurring was discussed according to the results of YAG laser welding processing. The methods how to reduce weld porosity for laser welding of Aluminum-Lithium alloy was also described.