• 한국표면공학회지
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• 제34권2호
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• pp.161-168
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• 2001

A Thermal Barrier Coating (TBC) can play an important role in protecting parts from harmful environments at high temperatures such as oxidation, corrosion, and wear in order to improve the efficiency of aircraft engines by lowering the surface temperature of the turbine blade. The TBC can increase the life span of the product and improve the operating properties. Therefore, in this study the mechanical and thermal properties of the TBC such as oxidation, fatigue and shock at high temperatures were evaluated. A samples of a bond coat (CoNiCrAlY) produced by the High Velocity Oxygen Fuel (HVOF) and Low Pressure Plasma Spray (LPPS) method were used. The thickness of the HVOF coating layer was approximately $450\mu\textrm{m}$ to 500$\mu\textrm{m}$ and the hardness number of the coating layer was between 350Hv and 400Hv. The thickness of the LPPS coating was about 350$\mu\textrm{m}$ to 400$\mu\textrm{m}$ and the hardness number of the coating was about 370Hv to 420Hv. The X-ray diffraction analysis showed that CoNiCrAlY coating layer of the HVOF and LPPS was composed of the $\beta$and ${\gamma}$phase. After the high temperature oxidation test, the oxide scale with about l0$\mu\textrm{m}$ to 20$\mu\textrm{m}$ thickness appeared at the coating surface on the Al-depleted zone was observed under the oxide scale layer.

• 한국표면공학회지
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• 제34권1호
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• pp.3-9
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• 2001

The purpose of this study is to evaluate the properties of the functional gradient thermal barrier coatings by plasma spray process. The evaluations of mechanical and thermal properties such as fatigue, oxidation and wear-resistance at high temperatures have been conducted. Furthermore, residual stress and bond strength have been evaluated. The range of thickness of coated layers was 550~600$\mu\textrm{m}$. The range of hardness of layers was 800~900 Hv and the porosity range of coatings was about 7 to 14%. The top coating layer of $ZrO_2$ in thermal barrier was composed of tetragonal structure after spraying. The coated layers of $ZrO_2$ on the Inconel substrate is the best resistance for thermal fatigue. Those coatings had the least compressive stress in comparison with other coatings. In high temperature oxidation test, the coatings on Inconel substrate was better than the coatings on SUS substrate. The bond strength of the concave type was greater than that of linear types and convex types coatings.

• Design & Manufacturing
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• 제15권3호
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• pp.7-12
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• 2021

Plastic injection molds used for rapid heating and cooling must minimize surface damage due to friction and maintain excellent thermal and low electrical conductivity. Accordingly, various surface treatments are being applied. The properties of Al₂O₃ coating and DLC coating were compared to find the optimal surface treatment method. Al₂O₃ coating was deposited by thermal spray method. DLC films were deposited by sputtering process in room temperature and high temperature PECVD (Plasma enhanced chemical vapor deposition) process in 723 K temperature. For the evaluation of physical properties, the electrical and thermal conductivity including surface hardness, adhesion and wear resistance were analyzed. The electrical resistance of the all coated samples was showed insulation properties of 24 MΩ/sq or more. Especially, the friction coefficient of high temp. DLC coating was the lowest at 0.134.

• 한국재료학회지
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• 제25권5호
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• pp.226-232
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• 2015

본 연구에서는 손상된 알루미늄 금형의 복원을 위해 고온플라즈마 용사법을 이용하여 금형의 표면에 $Al/Al_2O_3$ 혼합분말을 용사한 후 코팅층과 모재의 증착강도에 대한 평가를 수행하였다. 증착강도의 평가는 분사노즐의 이동속도, 순수한 알루미늄 bond coat 층의 유무에 따라 평가되었으며, bond coat 층을 생성시키지 않았을 때, 코팅층의 두께는 열팽창에 의한 잔류인장응력의 감소를 위해 두껍지 않아야 하지만 일정두께 이상이 되어야 최대의 증착강도를 얻을 수 있음이 나타났다. 또한 순수한 알루미늄 bond coat 층은 내부 결함이 없는 응고된 금속이기 때문에 두께에 따른 증착강도의 영향을 그대로 받아 두께가 두꺼울수록 bond coat 층을 생성시키지 않은 시험편보다 증착강도가 매우 낮게 측정되었다. 반면, 가장 얇게 bond coating 된 시험편 Bc3(3회의 bond coating층과 분사건의 이동속도가 20 cm/sec인 시험편) 는 bond coating을 하지 않은 시험편 중 가장 높은 증착강도를 가지는 시험편 Wbc20(bond coating층이 없고 분사건의 이동속도가 20 cm/sec인 시험편)보다 약 2배 이상증착강도가 향상되었다. 따라서 금형의 복원시에 중간층의 형성이 반드시 필요하며, 이는 코팅층의 잔류 인장응력을 보완시키며 고인성의 순수한 알루미늄과 같은 코팅층과 유사한 층을 코팅하는 것이 필요한 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제10권6호
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• pp.643-651
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• 1997

This experiment was conducted to determine apparent ileal and fecal digestibilities of protein sources for young pigs (15.6 kg BW) which were fitted with simple ileal T-cannulas. Experimental diets included one of the followings as a sole protein source: spray-dried plasma protein (SDPP), spray-dried blood meal (SDBM), soybean meal (SBM), isolated soy protein (ISP), dried skim milk (DSM), and fish meal (FM). The digestibilities of dry matter (DM), gross energy (GE) and crude protein (CP) in DSM-based diet were the highest (p < 0.05), and those of SDBM and SBM diets were the lowest at the terminal ileum. The average ileal digestibilities of essential amino acids (AAs) were 88.3, 84.7, 84.6, 83.4, 83.0 and 77.7% for pigs fed the DSM, ISP, SDBM, SBM, SDPP and FM diets, respectively. There were no significant differences in overall apparent ileal AAs digestibilities in DSM and ISP diets. Digestibilities of essential AAs in DSM, however, were significantly higher than those of ISP (p < 0.05). Among the essential AAs, the digestibility of arginine was higher except for SDBM or DSM, than other AAs. The ileal digestibilities of lysine, methionine and threonine were higher (p < 0.05) in pigs fed SDBM or DSM diet than in those fed SBM diet. Digestibilities for SDPP or ISP diet in these AAs were similar except for threonine which was higher (p < 0.05) for SDPP diet. The apparent ileal digestibilities of lysine and methionine ranged from 79.6 (FM) to 92.5 (DSM) and 75.4 (SDPP) to 88.7 (DSM), respectively. The apparent fecal digestibilities of average essential AAs were 90.4, 89.1, 86.0, 84.4, 84.2 and 80.8% in pigs fed the DSM, ISP, SDBM, SDPP, SBM and FM diets, respectively. The fecal digestibilities of essential AAs were higher (p < 0.05) in pigs fed the DSM and ISP. Lysine digestibility in pigs fed the DSM or ISP diet was higher (p < 0.05) than that of pigs fed SBM diet. Apparent essential AAs digestibility was the highest (p < 0.05) in pigs fed DSM diet, and was the lowest (p < 0.05) in pigs fed FM diet. Digestiibilities of essential AAs and nonessential AAs were higher when measured over the total digestive tract than at the end of the small intestine except for several AAs in SDPP, SDBM and SBM diets. In conclusion, whether it is fecal or ileal, the digestibilities of proximate nutrients and AAs in pigs fed DSM and ISP diet were the highest, and those of pigs fed FM was the lowest.

• Asian-Australasian Journal of Animal Sciences
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• 제22권7호
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• pp.1032-1037
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• 2009

The present experiment was conducted to study the effects of partial replacement of spray-dried porcine protein (SDPP) or fish meal with soybean and shrimp protein hydrolysate (SSPH) on growth performance, nutrient digestibility and serum biochemical parameters in weaned pigs. Two hundred and forty 21${\pm}$2 d old pigs ((Pietrain${\times}$Duroc)${\times}$(Landrace${\times}$Large Yorkshire)) with initial weight of 6.9${\pm}$0.5 kg were randomly allocated to five dietary treatments with six replicates per treatment and eight piglets per replicate. The control diet (T1) contained 2% SDPP and 6% fishmeal, and SDPP for experimental diets T2 and T3 was replaced with 1% and 2% SSPH, respectively, on an iso-nitrogenous basis. The fishmeal for experimental diets T4 and T5 was replaced with 1% and 2% SSPH, respectively, also on an iso-nitrogenous basis. The experimental period was 21 days. The results showed that weaned piglets fed the diets containing 1% and 2% SSPH as a replacement for SDPP had similar average daily gain (ADG), average daily feed intake (ADFI), feed/gain (F/G), diarrhea rate and serum biochemical indices e.g. blood urea nitrogen (BUN), total serum protein (TP), albumin to globulin ratio (A/G), globulin (GLO), serum glucose (GLU), and immunoglobulin G (IgG) to those fed the control diet during 0-10 d and 0-21 d of the experiment. The substitution of 1% SSPH on an iso-nitrogenous basis for fish meal appeared to be beneficial for ADG (p = 0.59) and ADFI (p = 0.23) of piglets during the overall period. The digestibility of calcium was higher (p<0.01) in pigs fed diets containing SSPH than on the control diet. Addition of 1% SSPH on an iso-nitrogenous basis for fish meal could increase the digestibilities of dry matter and energy of the diet. Dietary replacement of fish meal with 1% and 2% SSPH had no effect on the concentrations of BUN, TP, A/G, GLO, GLU, and IgG. In conclusion, dietary SDPP or fish meal could partially replace SSPH without any adverse effect on growth performance, nutrient digestibility and serum biochemical parameters in weaned piglets.

• 비파괴검사학회지
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• 제29권5호
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• pp.450-457
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• 2009

열차폐 코팅 시편에 대하여 열충격을 주기적으로 가한 후 발생하는 결함을 관찰하였다. 실험에 사용 된 열차폐 코팅 시편은 인코넬-738로 제작된 모재 위에 CoNiCrAlY 본드 코팅층과 $ZrO_2-8wt%Y_2O_3$ 세라믹탑 코팅층이 플라즈마 용사 방법으로 올려진 형태로 되어있다. 열충격 시험은 $1000^{\circ}C$의 고온으로 가열했다가 상온으로 급격하게 냉각시키는 가혹한 조건으로 실행되었고, 사이클 수가 증가함에 따라 열충격의 피로도 또한 증가하였다. 시험후 시편 내부의 미세 조직 변화와 결함을 전자현미경으로 관찰하고, 시편의 기계적인 특성을 측정하여 그 변화 양상을 살펴보았다. 열충격 주기실험후 본드 코팅층과 세라믹 탑 코팅층 사이에 발생하는 TGO 산화물층에 대한 변화 양상과 이에 대한 와전류 신호를 측정하여 TGO층 성장 거동의 비파괴적인 평가를 위한 실험을 진행하였다. 본 연구를 통하여 마이크로 단위의 TGO층에 대한 와전류검사의 적용 가능성을 확인하고 열차폐 코팅의 수명을 예측할 수 있는 가능성을 제시하였다.

• 한국재료학회지
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• 제10권4호
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• pp.312-316
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• 2000

HIP처리가 가스터빈 고정익 등 고온부품에 적용되는 열차폐 코팅층의 접착강도 및 고온특성에 미치는 영향을 조사하였다. 시편은 IN738LC 초합금 표면에 8wt%Y$_2$O$_3$-$ZrO_2$분말을 플라즈마 용사법으로 코팅한 후 $1200^{\circ}C$, 100MPa의 고온, 고압에서 4시간 동안 HIP 처리하여 준비하였다. 실험결과 HIP 처리된 코팅의 경우 미세균열과 기공이 상당량 감소하였으며 EDX분석을 통해 계면에서 원자간 상호확산이 발생한 것을 확인하였다. 이러한 코팅층의 치밀화 및 상호확산으로 인해 HIP처리된 코팅층의 접착강도는 48% 이상 크게 증가하였으며 조직 또한 균질화 되었다. 반면 가열과 냉각이 반복되는 환경에서 코팅층의 내구력은 HIP 처리된 경우가 다소 저하되었다. 이는 코팅과 모재와의 열팽창 차이로 인한 변형을 완화시켜주는 기공과 미세균열이 감소되었기 때문으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.72.2-72.2
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• 2010

평판형 고체산화물 연료전지 스택의 고온 밀봉 구조에 대하여 설명하고 스택 운전 후 사후 분석을 통하여 밀봉재와 금속 분리판의 계면반응에 대하여 고찰하였다. 대표적인 고온 밀봉재인 Barium-Silicate 계 결정화 유리와 Fe-Cr 계 금속 분리판은 스택의 작동온도인 $700{\sim}850^{\circ}C$ 에서 고온 반응을 통하여 계면에 반응생성물을 형성하는 것이 확인되었다. 이러한 계면반응은 장기 운전시 SOFC 스택 성능 저하의 원인이 되고, 열 싸이클(작동온도${\leftrightarrow}$상온)을 가하면 계면반응 생성물이 delamination 되어 밀봉구조가 파괴되어 수명을 단축시키게 된다. 계면반응은 Fe-Cr 계 금속 분리판의 산화물인 Cr 산화물, Fe 산화물이 밀봉유리 소재와 반응을 일으키는 것이 주요 원인으로 판명되었다. SOFC 스택에서 열 싸이클시 계면반응에 의하여 기밀도가 감소하는 현상이 확인되었으며, 밀봉 구조의 어느 부분에서 계면반응이 진행되는지 관찰하였다. 이러한 계면반응을 막기 위해서는 금속 분리판과 밀봉유리 사이에 계면반응을 억제하는 보호층을 형성하는 방법이 효과적이다. 본 연구에서는 보호층으로서 밀봉유리 및 Fe-Cr 계 금속 분리판과의 계면반응성이 낮고 열팽창 계수가 비슷한 Yttria Stabilized Zirconia 층을 APS(Atmospheric Plasma Spray) 공정을 이용하여 형성하였다. 밀봉유리/YSZ 보호층/금속분리판은 gas-tight 한 밀봉 구조를 형성하였으며, YSZ 보호층은 밀봉유리와 Fe-Cr 계 금속 분리판 소재와 계면반응을 효과적으로 억제하는 것이 확인되었다.

• 대한치과보철학회지
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• 제29권3호
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• pp.55-74
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• 1991

The purpose of this study was to investigate the influence of early functional load around osseointegrated titanium implants. 24 titanium plasma spray coated implants (ITI HS-type) were placed into the previously extracted site in the mandible of six adult dogs. The implants were divided into three groups : the control group was the implants without abutment during the experimental period; the experimental group I was loaded by connecting the contoured abutment after 6 weeks of healing; the experimental group II was loaded after 12 weeks of healing: and the mandibular second premolar and surrounding tissues were selected for natural tooth group to compare the implanted group. All dogs were injected intravenously tetracycline, alizarin red S, and calcein for bone labeling. After the experimental period of 18 weeks, the dogs were sacrificed and longitudinal sections of the bone-implant interface were cut and observed using light microscope, scanning electron microscope, and fluorescence microscope. The results of the study were as follows: 1. Light and scanning electron microscopically, all implant surfaces were well contact with bone tissue at the cortical layer, but some areas of cancellous bone were not contact directly. 2. Fluorescence microscopically, number and size of the new secondary osteons around the implant were increased than those of the natural tooth. 3. Fluorescence microscopically, linear and concentrical fluorescence was observed at or near the surface of all implants, and the bone formation and remodeling of the implants loaded after 6 week of healing were great, and unloaded implants were worst. 4. Fluorescence microscopically, endosteal bone formation was greater than periosteal bone formation at or near the implants. 5. Fluorescence microscopically, number and size of linear and concentric fluorescence was increased at the lingual side than the buccal side of the loaded implants. The result of the study indicate the possibility of the early load to the implant via a prosthesis.