Papers by Keyword: Coating Film

Abstract: Thermoelectric materials can directly convert thermal energy into electrical energy, realizing the recovery of waste heat. Bismuth Telluride (Bi-Te) is considered as a perfect candidate thermoelectric material which has great potential in the field of refrigeration and temperature sensor. However, in the field of intelligent wearable devices and integrated circuits, traditional Bi-Te block material is difficult to be directly used due to its poor flexibility. In this paper, a series of Bi-Te thin films were prepared by a self-designed high-temperature thermal shock equipment. This equipment can heat up the reduced graphene oxide strip to 1750 K in 20 ms, which features both high heating rate (8.2 × 10⁴ K/s) and cooling rate (1.5 × 10⁴ K/s). Thermoelectric films on different substrates were prepared via high-temperature thermal shock. Through regulating the temperature of evaporation source, the particle size and composition of Bi-Te thin films can be precisely modulated, thus optimizing the Seebeck coefficient of the films. The Seebeck coefficient of copper foil (Cu_f)-based Bi-Te film can reach 345.41 μV/K, which was prepared by thermal-shocking the Bi-Te powders for 30 s at 900°C.

Abstract: This paper aims to evaluate residual stress of coated film on cold work tool steel grade SKD11 (JIS) substrate. Four types of film coating were deposited on hardened SKD11 steel. Mechanical property of film coatings was examined by nano-indentation. The thickness of the films was analyzed by scanning electron microscopy (SEM). Residual stress of coated film was investigated by using curvature technique based on the Stoney equation. The results of them were compared and correlated to the bond strength of the films from scratch testing. The influences of residual stress on bond strength of the films were thoroughly discussed in details.

Abstract: The preservation of Synsepalum dulcificum has been researched by using chitosan coating as the antistaling agent at room temperature. The physicochemical indexes, such as rot rate, weight loss ratio, scavenging capability of DPPH• radical, total acidity and sensory quality, were assayed during the process of storage. The optimum formulation of the fresh-keeping agent was as follows: 1.5% chitosan, 1% ascorbic acid, 0.1% Tween-80 and 1.0% glycerol. The results showed that the coating films could effectively decrease the loss of fruit nutrition and weight-loss ratio, inhibited the respiration and delayed the senescent course during storage.

Abstract: Several sol solutions were synthesized by using two kinds of nanosized boehmite and methyltrimethoxysilane (MTMS) according to the changing amount of MTMS at different reaction time. To understand their physical and chemical properties, sol-gel coating films were fabricated on glass. The sol solutions were prepared from boehmite of spherical shape (boehmite1)/MTMS and mixed boehmites of spherical and fibrous shapes (boehmite2)/MTMS. The soluble stability of boehmite1/MTMS was observed in the sol solution left for 24 h, however, that of boehmite2/MTMS was observed in the sol solution left for 48 h. The contact angle of sol-gel coating films from boehmite/MTMS increased with MTMS contents and reaction time. The films formed a flat surface with the increasing MTMS contents and decreasing reaction time. The electrical resistivity of films increased with MTMS contents. The thermal degradation of films occurred at approximately 400 oC.

Abstract: Film-coating on the surface of titanium was investigated by hydrothermal treatments with a maximal pressure of 6.3 MPa (280°C) in CaO solution and water to improve bioactivity and biocompatibility. As a result, calcium titanate (CaTiO3) film was formed on the titanium surface. The surface-coated titanium was immersed in a simulated body fluid (SBF) to estimate its bioactivity. Apatite precipitation was observed on all hydrothermal-treated titanium surfaces after immersion in SBF for 4 weeks. In particular, the apatite precipitation of titanium treated with 6.3 MPa in CaO solution was clearer and larger in amount than those of all other hydrothermal-treated specimens. The results suggest that surface modification of titanium with high-pressure hydrothermal treatments can be expected to improve bioactivity and biocompatibility.

Abstract: TiO2 coating films of 50-200nm thickness were prepared by the sol-gel technique using hydrolysis of titanium isopropoxide (TIP) in an attempt to study structure and surface properties of anatase at ambient temperature. The anatase phase is exhibited by the XRD peak at 2θ'=25o with orientation in (101), the crystal parameters of XRD for TiO2 thin films (50-200 nm), were varied depending on the thickness of film and substrate type. An annealing temperature and annealing time had an effect on the film surface quality and exhibit porosity and aggregates in the films. The surface of TiO2 thin film showed cluster particles through SEM and the shrinkage rate on the film increased as a result of heat treatment during annealing process. The film was uniform and homogeneous under AFM investigate. EDS have determined the stochiometric ratio of TiO2 film.