• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.11
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• pp.690-695
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• 2016

Induction cooktop has a great attention due to its safety, quick heating and cleanness compared to gas oven. However, the materials for induction cookware is limited to steel or stainless-steel which has the magnetic property. Recently, it has been tried to apply various porcelain to induction cookware after printing the silver layer on the bottom of cookware plates and co-firing at high temperature. Glass frits are added in the silver paste to improve an adhesion force between porcelain materials containers and transferred silver layer. The hybrid silver pastes for induction cookware requires the proper electrical resistance and the thermal conductivity with base plates. After sintering process at $800^{\circ}C$, a part of melted glass migrated to the porcelain and the rest of the glass frit was exposed to the surface. It was confirmed that most of the glass frit formed an adhesion layer between the porcelain and transferred silver layer that enhances the adhesion force.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.395-402
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• 2015

The suspension plasma spray (SPS) technique has been used to obtain dense $Y_2O_3$ coatings and to overcome the drawbacks of the conventional air plasma spray (APS). SPS uses suspensions containing micrometer or sub-micrometer sized powders dispersed in liquid media. In this study, microstructure developments and mechanical properties have been investigated as functions of particle size of source material and plasma processing parameters such as plasma power and stand-off distance. The microstructure of the coating was found to be highly related to the particle size and the plasma processing parameters, and it was directly reflected in the hardness and the adhesion strength. When fine powder (BET $16.4m^2/g$) was used as a raw material in the suspension, there was, with increasing stand-off distance, a change from a dense structure with a slightly bumpy surface to a porous structure with a cauliflower-like surface. On the other hand, when a coarse powder (BET $2.8m^2/g$) was used, the coating density was lower, with microscopic splats on the surface. Using fine $Y_2O_3$ powders, the coating layer with an optimum short stand-off distance showed a high hardness of approximately 90% of that of sintered $Y_2O_3$ and an adhesion strength several times higher than that of the coating by conventional APS.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.497-504
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• 2009

DLC is considered as the candidate material for application of moving parts in automotive components relatively in high pressure and temperature operating conditions for its high hardness with self lubrication and chemical inertness. Different deposition method such as arc plating, ion gun plating and PECVD were used for comparing mechanical and tribological properties of each DLCs deposited on stainless steel with 1 um thick respectively. Among these 3 types of DLCs, the arc plated DLC film showed highest value for wear resistance in dry condition. From the results of analysis for physical properties of DLC films, it seems that the adhesion force and crack initiation modes were more important factors than intrinsic mechanical properties such as hardness, elastic modulus and/or roughness to the wear resistance of DLC films. Raman spectroscopy was used for understanding chemical bonding natures of each type of DLC films. Typical D and G peaks were identified based on the deposition method. Hardness of the coating layers were identified by nanoindentation method and the adhesions were checked by scratch method.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.405-412
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• 2009

The purpose of this study investigated the effect of Au coating on adhesion between porcelain matrix and metal substructure interface. Titanium, Ni-Cr alloy and Co-Cr alloy are well known as proper metal for the dental restorations. The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. However, adhesion between dental alloys and porcelain is related to diffusion of oxygen during ceramic firing. The excessive oxidized layers make hard adhesion between dental alloy and ceramic. Ni-Cr and Co-Cr specimens were divided into test and a control group and Titanium specimens were divided into three test groups and a control group. Each group had 20 specimens. The adhesion characteristics of porcelain and metal with Au coating layer and without Au coating layer were observed with scanning electron microscopy(SEM). The adhesion was evaluated by a biaxial flexure test and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that Au coating layer is effective barrier to diffuse oxide layer completely protect non-precious alloys from oxidation during the porcelain firing. The SEM photomicrographs of cross-section specimens showed a smooth interface between Au coating layer and metals and porcelain which suggested proper chemical bonding, and no gap, porosity were observed. The mode of failure was mainly adhesive for Ti tested specimens, but mixed failures with adhesive and cohesive were observed in Ni-Cr and Co-Cr specimens. The adhesion between non-precious metals and porcelain would not be improved by Au coating agent. However, It is suggested that the continuous study is required further investigation and development.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.105-109
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• 1997

The effects of surface conditions of the C-2 cemented carbide substrate on the adhesion of diamond film were investigated. The substrates were pretreated for different times with Murakami's reagent and then the acid solution of an H2SO4-H2O2. The adhesion strength was estimated by a peeling area around the Rockwell-A indentation. The cutting performance of the diamond-coated tools was evaluated by measuring flank wears in dry turning of Al-17% Si alloy. The morphology of deposited diamond crystallites was dominated by (111) and (220) surfaces with a cubooctahedral shape. The diamond film quality was hardly affected by the surface conditions of the substrate. The variation of tool life with longer substrate etching times resulted from a compromies between the increase of film adhesion at the interface and the decrease of toughness at the substrate surface. The coated tools were mainly deteriorated by chipping and flaking of the diamond film form a lock of adhesion strength, differently from the wear phenomena of PCD tools.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.601-610
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• 2007

Statement of problem: The adhesion between titanium and ceramic is less optimal than conventional metal-ceramic bonding, due to reaction layer form on cast titanium surface during porcelain firing. Purpose: This study characterized the effect of titanium-ceramic adhesion after gold and TiN coating on cast and wrought titanium substrates. Material and method: Six groups of ASTM grade II commercially pure titanium and cast titanium specimens$(13mm{\times}13mm{\times}1mm)$ were prepared(n=8). The conventional Au-Pd-In alloy served as the control. All specimens were sandblasted with $110{\mu}m\;Al_2O_3$ particles and ultrasonically cleaned for 5min in deionized water and dried in air before porcelain firing. An ultra-low-fusing dental porcelain (Vita Titankeramik) was fused on titanium surfaces. Porcelain was debonded by a biaxial flexure test at a cross head speed of 0.25mm/min. The excellent titanium-ceramic adherence was exhibited by the presence of a dentin porcelain layer on the specimen surface after the biaxial flexure test. Area fraction of adherent porcelain (AFAP) was determined by SEM/EDS. Numerical results were statistically analyzed by one-way ANOVA and Student-Newman-Keuls test at ${\alpha}=0.05$. Results: The AFAP value of cast titanium was greatest in the group 2 with TiN coating, followed by group 1 with Au coating and the group 3 with $Al_2O_3$ sandblasting. Significant statistical difference was found between the group 1, 2 and the group 3 (p<.05). The AFAP value of wrought titanium was greatest in the group 5 with TiN coating, followed by the group 4 with Au coating and the group 6 with $Al_2O_3$ sandblasting. Conclusion: No significant difference was observed among the three groups (p>.05). The AFAP values of the cast titanium and the wrought titanium were similar. However the group treated with $Al_2O_3$ sandblasting showed significantly lower value (p<.05).

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.73-81
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• 1997

In this paper, it is intended to present more reproducible and quantitative method for adhesion assemssement. In scratch test, micromechanical analysis on the stress state beneath the indenter was carried out considering the additional blister field. The interface adhesion was quantified as work of adhesion through Griffith energy approach on the basis of the analyzed stress state. The work of adhesion for DLC film/WC-Co substrate calculated through the proposed analysis shows the identical value regardless of distinctly different critical loads measured with the change of film thickness and scratching speed. On the other hand, uniaxial loading was imposed on DCL film/Al substrate, developing the transverse film cracks perpendicular to loading direction. Since this film cracking behavior depends on the relative magnitude of adhesion strength to film fracture strength, the quantification of adhesion strength was given a trial through the micromechanical analysis of adhesion-dependence of film cracking patterns. The interface shear strength can be quantified from the measurement of strain $\varepsilon$s and crack spacing $\lambda$ at the cessation of film cracking.

• Korean Journal of Materials Research
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• v.10 no.8
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• pp.575-580
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• 2000

Diamond thin films were deposited on $Si_3N_4$, SiC, TiC and $Al_2O_3$, substrates by the CVD method using Ta(TaC)Filament, and the appearance of the diamond films and their adhesion properties were examined by SEM, optical microscopy, indentation test and compression topple test. Diamond films were deposited at lower $CH_4$ concentration than 5%$CH_4$ for all kinds of the substrate material, but graphitic(amorphous)carbon was observed at 10%$CH_4$. The diamond film of about $12\mu\textrm{m}$ thickness on WC substrate partly peeled off, but the film on $Si_3N_4$ substrate held good adhesion. The indentation test showed that roughly ground surface was very effective for adhesion of diamond films to substrate. The topple test revealed that film thickness was an important factor governing the adhesion of the diamond film.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.549-553
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• 2014

$CoSb_3$-based skutterudite compounds are candidate materials for thermoelectric power generation in the mid-temperature range (600 - 900 K) because their thermoelectric properties can be enhanced by doping and filling. The joining property of thermoelectric module electrodes containing thermoelectric materials is of great importance because it can dominate the efficiency of the thermoelectric module. This study examined the properties of $CoSb_3$/Al/Ti/CuMo joined by the spark plasma sintering technique. Titanium thin foil was used to prevent the diffusion of copper into $CoSb_3$ and Aluminum thin foil was used to improve the adhesion between $CoSb_3$ and Ti. The insertion of an Aluminum interlayer between the Ti and $CoSb_3$ was effective for joining $CoSb_3$ to Ti by forming an intermediate layer at the Al-$CoSb_3$ boundary without any micro cracks. Specifically, the adhesion strength of the Ti/Al/$CoSb_3$ joining interface showed a remarkable improvement compared with our previous results, without deterioration of electrical property in the interface.

• Proceedings of the Korean Ceranic Society Conference
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• 1986.12a
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• pp.269-286
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• 1986