• Journal of the Korean Applied Science and Technology
• /
• v.22 no.3
• /
• pp.234-240
• /
• 2005

In this study, we have prepared three kinds of enteric tablet coating formulations for prevention the crack incidence and enhanced process improvement of enteric tablet using aqueous system. we determined the mechanical strength of three formulatons on the enteric film-coating process. The compared experiment of one-layer and two-layer (A), (B) coating treated having placebo tablets without breakline and logo. In result, the breaking force time of two-layer (B) film strength was found to increase 0.8min than two-layer (A). We confirmed the half reduction of working hour and the simplification in the one-layer coating process, and the coating troubles was solved as setting up a dehumidifier in inlet of coater. In result, we recovered that optimum running capacity(g/kg) of dehumidifier is 10g/kg and below.

• Journal of the Korean Ceramic Society
• /
• v.44 no.7
• /
• pp.368-374
• /
• 2007

CVD-SiC coating has been introduced as a protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor (HTGR) due to its excellent mechanical stability at high temperature. In order to prevent the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. It is needed to develop a new simple characterization technique to evaluate the mechanical properties of the coating layer as a pre-irradiation step. In present work, direct strength measurement method with the specimen of hem i-spherical shell configuration was suggested. The indentation experiment on a hemisphere shell with a plate indenter was conducted. The fracture strength of the coating layer is related with the critical load for radial cracking of the shell. The finite element analysis was used to drive the semi-empirical equation for the strength measurement. The SiC hemispherical shells were successfully recovered from the section-grinding of TRISO coated particle and successive heat treatment in air. The strength of CVD-SiC coating layer was evaluated from the experimentally measured critical load during the indentation on SiC hemisphere shell. Weibull diagram of fracture strength was also constructed. This study suggested a new strength equation and experimental method to measure the fracture strength of CVD-SiC coating of TRISO coated fuel particles.

• Journal of Welding and Joining
• /
• v.10 no.4
• /
• pp.181-189
• /
• 1992

The purpose of this investigation is to examine the effects of the strengthening treatments on the mechanical properties of the flame-sprayed titania ceramic coating layer. The strengthening treatments for flame sprayed specimens were carried out in 12 different conditions in vaccum furance. The mechanical properties such as microhardness, thermal shock resistance, adhesive strength and erosion resistance were tested for the sprayed specimens after strengthening treatments. And it was clear that the mechanical properties of coating layer were much improved by the strengthening treatments. The results obtained are summarized as follows; 1. It was shown that the metallurgical bond was formed between substrate and coating layer by the strengthening treatments and that thermal shock resistance and adhesive strength were remarkably raised. 2. Microhardness of coating lay was considerably increased by the strengthening treatments. 3. Erosion resistance and porosity of coating layer were slightly improved by the strengthening treatments.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2003.10a
• /
• pp.59-59
• /
• 2003

In recent, various functional coatings on artificial tooth implants have been conducted to enhance the bonding strength between implants and bones. Despite of these efforts, some previous reports argued that an adhesion strength between titanium implant and the final coatings like hydroxyapatite(HA) is weaker than the strength between coating and bone. In order to increase the adhesion force between the final coating and implant surface, TiN/DLC based functionally graded coating, which has higher mechanical strength than the titanium implant, was applied as a middle layer between titanium implant and final coating. Particularly we finally coated a biocompatible hydroxyapatite film on the DLC layer and examined the mechanical properties. As a result, TiN/DLC based functionally graded coating showed the higher adhesion strength compared with hydroxyapatite single layer coating on the titanium implant.

• Journal of Welding and Joining
• /
• v.25 no.4
• /
• pp.65-71
• /
• 2007

Laser weldability of the aluminized steel for the full penetration welding will be described in this paper. We focused on the effect of Al coating conditions on weld strength. For these objectives, aluminized steel sheets that have various thickness and coating weight were prepared for laser welding. And then, tensile-shear and hardness test were carried out. At the same time, Al contents in weld after laser welding were analyzed and their correlations with mechanical properties were investigated. Besides, as removing partially coating layer, weldability has been investigated according to the position of coating layer. As a result of this study, tensile-shear strength was decreased with increasing Al contents in weld, and Al of coating layer caused grain growth.

• Journal of the Korean Ceramic Society
• /
• v.43 no.8 s.291
• /
• pp.492-497
• /
• 2006

SiC coating has been introduced as protective layer in TRISO nuclear fuel particle of High Temperature Gas cooled Reactor (HTGR) due to excellent mechanical stability at high temperature. In order to inhibit the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. ]n present work, thin silicon carbide coating was fabricated using chemical vapor deposition process with different microstructures and thicknesses. Processing condition and surface status of substrate.affect on the microstructure of SiC coating layer. Sphere indentation method on trilayer configuration was conducted to measure the fracture strength of the SiC film. The fracture strength of SiC film with different microstructure and thickness were characterized by trilayer strength measurement method nanoindentation technique was also used to characterize the elastic modulus and th ε hardness of the SiC film. Relationships between microstructure and mechanical properties of CVD SiC thin film were discussed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.30 no.3
• /
• pp.63-72
• /
• 1998

This research was intended to evaluate the effect of carboxymethylcellulose(CMC) on the coating structure and surface strength of coated paper prepared with amphoteric latex based coating color. Printability and optical properties of coated papers were compared. The influence of the consolidation behavior of coating color on the coating structure and the surface strength of coated paper was investigated. Compared with the conventional anionic latex, amphoteric latex formed bulkyer, smoother and more porous coating layer, which in turn, restricted binder migration in the coating layers, and facilitated immobilization of coating colors. However, dry pick strength of coated paper was decreased. The addition of CMC to these systems had strongly influenced on. the consolidation behavior and porosity in the dry state, through forming the network structure of coating layers by the interaction with amphoteric latex particles. Thus, printability and optical properties of coated papers were improved. Results indicated that amphoteric latex could be practically applied to the paper coating to improve printability and optical properties of coated papers.

• Journal of Surface Science and Engineering
• /
• v.22 no.4
• /
• pp.185-196
• /
• 1989

The surface modification of a mild and stainless steel by alumina sprayed coating were studied. The effects of surface roughness and bond coating layer on the adhesive strengthy and durability of sprayed specimens were also investiated. The adhesive strength of ceramic coating was affected by surface roughness and bond coating layer thinkness. That showed excellent undergrit blast time and bond coating layer; 60 sec and 0.15-0.33mm, respectively. The adhesive strength and densification of sprayed coating with air pressure were superior to those of without and fracture was mainly occured at alumina-bond coating interface. Under ambient atmosphere at $800^{\circ}C$, the oxides existed within bond coating layer promote diffusion of oxygen to lower durability of sprayed specimens. In this case, fracure was occured at sudstrate-bond coating interface.

• Journal of Welding and Joining
• /
• v.10 no.3
• /
• pp.26-39
• /
• 1992

Diffusion bonding of Mo was performed by using the metallic coating of Cu and Cr on the surface to be bonded. Joint characteristics of Mo with or without coating layer were compared in metallurgical and fractograpical aspects. The results showed that the diffusion bonding with coating layer, especially with Cu coating, increased the bending strength of joint. Variation of heating cycle(elevation of temperature for a moment) did not affect significantly the mechanical properties of joint. Fractographical analysis showed that the fracture of joint bonded with Cr coating occurred at the coating layer, while that with Cu coating occurred at the base metal.

• Journal of the Korean Ceramic Society
• /
• v.36 no.10
• /
• pp.1087-1093
• /
• 1999

Bioglass which is one of the surface active bionmaterials has a good biocompatibility but a poor mechanical strength, In the present work therefore two types of fluoride-containing bioglasses were coated on an alumina to improve mechanical strength. Crystallization of the coating layer and the hydroxyapatite formation on the bioactive glass coatings in tris-buffer solution were studied. When bioactive glass coated alumina was heat-treated Na2CaSi3O8 crystal was formed on the layer at lower temperature while wollastonite(CaSIO3) was obtained at higher temperature. Hydroxyapatite forming rate on the coating layer with Na2CaSi3O8 crystal was delayed with SiO2 contents in glass composition. However the hydroxyapatite was developed in 20minutes regardless SiO2 contents when the coating layer crystallized into wollastonite. More amount of P3+ ions were leached out of the coating layer with wollastonite than that with Na2CaSi3O8 crystal while Na+ and Ca2+ ions were leached out more easily from the Na2CaSi3O8 crystal containing coating layer.