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One of the techniques for modifying Ti implant surface is an anodization. This method is an electrochemical one that forms rough, thick, and porous oxide films. To compare the gene expression from the cells cultured on the different implant surface, cDNA microarray have been performed. MC3T3-E1 cells were cultured on titanium disks. The control groups were cultured on the machined surfaces(MS). The experimental groups cultured on the anodized titanium surfaces(AS). Microarray assay 48 hours after culturing the cells on the machined surface and anodized surface revealed that osteoinductive molecules appeared more prominent on the anodized surface, whereas the adhesion molecules on the biomaterial were higher on the machined surface than anodized surface, which will affect the phenotype of the plated cells depending on the surface morphology.

Because of its high biocompatibility, hydroxyapatite(HA) has been considered as a good blasting material. DNA microarray is a new molecular technology that enables the analysis of gene expression in parallel on a very large number of genes, spanning a significant fraction of the human genome. It is a qualitive analysis (e.g. it can differentiate each single gene) and quantitative, since it has the sensitivity to detect a change of expression level in the investigated cells when compared to normal samples. The aim of this study is to define the cell attachment and the genetic effect of machined surface implant and RBM (resorbable blast media) surface implant on the osteoblastic cell (MC3T3-E1 osteoblastic cell line) by cDNA microarray slide containing 21575 genes. Cells were cultured on machined grade 4 titanium disks(Group 1, machined surface) and disks of RBM (Group 2) and the samples were moved to new dishes and media were added and the plated disks were cultured for 24 hours. Total RNA extraction was performed with Qiagen mini kit (Qiagen, Chatsworth, CA, USA) for microarray assay. Microarray assay after culturing the cells on the machined surface and RBM surface revealed that osteoinductive molecules appeared more prominent on the RBM surface, whereas the adhesion molecules on the biomaterial were higher on the machined surface than RBM surface.

The adhesive and wear properties of ITO thin film have been investigated using the scratch and wear tests. ITO thin film was fabricated on glass substrate using RF magnetron sputter and strip lines were formed by selective etching. In the scratch test, the normal load on WC micro-blade was increased and kept constant as it was drawn over the films. In the wear test, sapphire, SUS and WC balls slided repeatedly on the films with the constant normal load. During the scratch and wear, the ESR and the acoustic signal were monitored and recorded. In order to study the adhesive and wear properties of ITO thin films, it was desirable to use the ESR rather than the acoustic signal. From the change in the ESR, it was possible to measure the critical load to cut through ITO film completely and the critical number of sliding to wear ITO film completely.

A porous filter was manufactured using cordierite powder by an extrusion method. The filter had an apparent porosity of 58% and a compressive strength of 10 MPa. Pulse cleaning process affected the durability of the filter. We investigated the effect of operating conditions of a hot gas cleaning system using ceramic filter, thermal shock and pressure shock on durability. When pulse cleaning was repeated periodically, the baseline differential pressure was relatively higher. On the other hand, when we repeated pulse cleaning per specific maximum differential pressure we could improve the durability of the filter. In our test conditions, thermal shock is the most important factor decreasing the durability of the filter. Pressure shock didn’t deteriorate the durability of the filter. However thermal shock caused the formation of cracks at the filter surface. This will lead to an increasing of the baseline differential pressure by depth filtration of dust and decrease the durability of the filter.

TiO2 coated open-cell mullite ceramics were fabricated with coating TiO2 sol on pores of mullite, and its processing parameters were investigated. Open-cell mullite ceramics were fabricated through a gel-casting process. Two kinds of mullite precursor powders were prepared by dissolution of two kinds of aluminum salts (Al(NO3)3·9H2O; type I and Al2(SO4)3·16H2O; type II) into colloidal silica sols. To produce porous mullite ceramics, both mullite precursor powders and PMMA beads (≈ 5μm) were co-dispersed by electrosteric stabilized mechanism in an aqueous system and then gel-casted. The green bodies were sintered above 1300°C for 3hrs in air. The PMMA was offered as pores in sintered mullite bodies. The prepared open-cell mullite ceramics were dipped in TiO2 precursor solution. The sintered bodies coated with TiO2 sols were re-sintered below 1000°C for 3hrs after drying at room temperature. The TiO2 was successfully coated into the open-cell mullite ceramics. The characteristics of each TiO2 coated porous mullite ceramics were investigated by XRD, SEM, porosimetry, as functions of aluminum salt and pH of sol. It was found that the synthesis behavior and the porosity of the mullite are strongly dependent upon aluminum salt species, resulting in different grain size, morphology, and pore size.

Wall and floor tiles were fabricated by a dry pressing method using waste glass and clay. The properties of the tiles such as absorption, bulk density, porosity, compressive strength, and abrasion loss are investigated with the firing temperature and glass content. The properties are improved with increasing both the firing temperature and glass content. These properties, except the compressive strength, tend to be saturated from the glass contents of 70 wt % in the case of 1050 . The compressive strength shows the maximum values at the glass contents of 70 wt% and then which are decreased with increasing the glass contents. The optimal properties obtained in the tiles are the water absorption of about 0.9 %, the bulk density of about 2.3 g/cm3, the apparent porosity of about 2.1 %, the compressive strength of about 210 MPa, and the abrasion loss of about 0.022 g, when the composition containing the glass of 70 wt% is fired at 1050. These results are better than the properties of commercial clay tiles, due to easy melting and densification of glassy phase in the tiles.

There is an increasing reliability concern of thermal stress-induced failures in multilevel coatings in recent years. This work reports investigations of cracking of NiCr coatings due to thermal cycling. The temperature cycling in accelerated testing was performed in three temperature range of 150, 175 and 200°C. The NiCr coatings were considered to have failed when the sheet resistance changed by 30% relative to an initial value. As the cyclic repetition of thermal shock increased, the sheet resistance of NiCr coatings increased. The Coffin-Manson equation was applied to the failure mechanism of cracking of NiCr coatings and the SEM observation of cracks and delamination in NiCr coatings due to thermal cycling agreed well with the failure mechanism.

Layered structures of dense porcelain/porous alumina and dense porcelain/porcelainalumina/ porous alumina are designed and their crack propagation behaviors are investigated. As a substrate, the porous alumina, which is prepared by a gel-casting process using the binary slip of alumina powder and PMMA spherical micro-bead, is dried at room temperature for 24 h and then sintered at 1600 for 2 h. Porcelain is coated on the porous alumina substrate and then re-sintered at 987. Bi- and tri-layered structures are produced by the different dwell times (2 min, 10 min) at re-sintering temperature. There is no delaminating or cracks observed after re-sintering the layered samples. The crack propagation behaviors in the bi- and tri-layered structures are evaluated by micro-indentation. The indentation cracks do not propagate into the porous alumina through interface (porosity; 36~62%) except for another one (porosity; 70%) in the bi-layered samples. In the case of the high porosity bi-layered sample (porosity; 70%), cracks are scattered along the 3-D open-pore channels. However, cracks do not propagate through the interface in the tri-layered samples with a porcelain-alumina buffer layer, because the porcelain-alumina buffer layer plays an important part such as a barrier layer in crack propagation.

Thermal degradation of indium tin oxide (ITO) thin film has been investigated. ITO thin film was fabricated on glass substrate using RF magnetron sputtering and was characterized. The resistivity of the film which was thermally degraded at high temperatures in air atmosphere was increased highly. Thermally-degraded specimen was analyzed using XPS and Hall measurement to reveal failure mechanism. Result showed that failure mechanism was the decrease in charge carrier concentration and mobility due to oxygen diffusion and chemisorption. Accelerated degradation test (ADT) was performed to predict the lifetime of ITO thin film. The lifetime under normal operating condition could be predicted via statistical analysis and modeling of data acquired from ADT of a short period.