• Title/Summary/Keyword: Al Powder spray

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Microstructural Evolution of Aluminum Nitride - Yttrium Aluminum Garnet Composite Coatings by Plasma Spraying from Different Feedstock Powders (Aluminum Nitride - Yttrium Aluminum Garnet 분말 특성과 플라즈마 용사 코팅층의 미세조직)

  • So, Woong-Sub;Baik, Kyeong-Ho
    • Korean Journal of Materials Research
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    • v.21 no.2
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    • pp.106-110
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    • 2011
  • A high thermal conductive AlN composite coating is attractive in thermal management applications. In this study, AlN-YAG composite coatings were manufactured by atmospheric plasma spraying from two different powders: spray-dried and plasma-treated. The mixture of both AlN and YAG was first mechanically alloyed and then spray-dried to obtain an agglomerated powder. The spray-dried powder was primarily spherical in shape and composed of an agglomerate of primary particles. The decomposition of AlN was pronounced at elevated temperatures due to the porous nature of the spray-dried powder, and was completely eliminated in nitrogen environment. A highly spherical, dense AlN-YAG composite powder was synthesized by plasma alloying and spheroidization (PAS) in an inert gas environment. The AlN-YAG coatings consisted of irregular-shaped, crystalline AlN particles embedded in amorphous YAG phase, indicating solid deposition of AlN and liquid deposition of YAG. The PAS-processed powder produced a lower-porosity and higher-hardness AlN-YAG coating due to a greater degree of melting in the plasma jet, compared to that of the spray-dried powder. The amorphization of the YAG matrix was evidence of melting degree of feedstock powder in flight because a fully molten YAG droplet formed an amorphous phase during splat quenching.

Optimization of the Plasma Spray Coating Parameters of Ni-5%Al Alloy Powder Using the Taguchi Experimental Method (다꾸찌방법에 의한 Ni-5%Al 합금 분말의 플라즈마 용사코팅 조건의 최적화)

  • 이형근
    • Journal of Welding and Joining
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    • v.20 no.5
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    • pp.120-126
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    • 2002
  • Ni-5%Al alloy powder is widely used as the bond coating powder to improve the adhesive strength between the substrate and coating. The important properties in the bond coating are the deposition efficiency and surface roughness. In this study, it was tried to optimize the plasma spray parameters to maximize the deposition efficiency and surface roughness. In the first step, spray current and hydrogen gas flow rate were optimized in order to increase the deposition efficiency. In the next step, the seven plasma spray variables were selected and optimized to improve both the deposition efficiency and surface roughness using the Taguchi experimental method. By these optimization, the deposition efficiency was improved from about 10 % at the frist time to 51.2 % by the optimization of spray current and hydrogen gas flow rate and finally to 65.2 % by the Taguchi experimental method. The average surface roughness was increased from about $12.9\mu\textrm{m}$ to $15.4\mu\textrm{m}$.

Effects of heat treatment on Fe-Al Alloy Layers Formed by Al Powder Spray (Al분말 분사에 의해 생성된 Fe-Al합금 피막층의 열처리에 따른 영향)

  • 양병모;박정직;박광정;박경채
    • Journal of Welding and Joining
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    • v.14 no.1
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    • pp.92-98
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    • 1996
  • Al-Fe alloy layers on heated steel sheet were made by Al powder spray for 30 minutes at $700^{\circ}C$, $800^{\circ}C$ and $1000^{\circ}C$, respectively. As a results, for alloy layers formed at $700^{\circ}C$ and $800^{\circ}C$, main phases were brittle phase $FeAl_3 and Fe_2Al_5$, hardnesses were very high (Hv 700~800), corrosion resistances were good and surfaces were smooth, but wear resistances were bad. For alloy layer formed at $1000^{\circ}C$, main phase was ductile phase $Fe_3Al$, hardness was low (Hv 300~400), corrosion and wear resistances were excellent, but surface was rough. Therefore, alloy layers that formed at $700^{\circ}C$ and $800^{\circ}C$ were heat treated at $1000^{\circ}C$ for 10 minutes for the purpose of smooth surface and excellent wear resistance in this study. It was investigated that brittle phase $FeAl_3 and Fe_2Al_5$ of alloy layers fromed by Al powder spray at $700^{\circ}C$ and $800^{\circ}C$ turn into ductile phase $Fe_3Al$ by heat treated at $1000^{\circ}C$ for 10 minutes without changing smooth surface. It was concluded that the alloy layers formed by Al powder spray on heated steel sheet at $700^{\circ}C$ and $800^{\circ}C$ for 30 minutes and heat treated at $1000^{\circ}C$ for 10 minutes were excellent on wear and smooth surface.

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A study on the improvement of frictional performance of friction material for automobile brake by spray treatment (용사처리에 의한 자동차 브레이크용 마찰재료의 마찰성능개선에 관한 연구)

  • 김윤해;배창원;손태관
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.1
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    • pp.67-76
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    • 1998
  • Friction materials for brake linings and clutches have severe performance requirements. The principal function of such frictional elements is to convert kinetic energy to heat, and then either to absorb or to dissipate heat. In order to achieve these objectives, the coefficient of friction must be as high as possible, independent of variations in operating conditions, and the necessary energy conversion must be accomplished with a minimum of wear on the contacting parts. In this study, Al powder, Al bronze powder and Mo powder used in general for automobile brake was sprayed on automobile brake disc to restrain rust and to maintain friction performance. Dynamo and corrosion tests have been carried out. It is concluded that the sprayed disc with Al bronze powder has the most improved frictional performance and anti-corrosive characteristics. The main results obtained can be summarized as follows; 1. From the corrosion current density test for gray cast iron and sprayed disc with powders of Al, Al bronze and Mo, it was cleared that the spray treatment with Al bronze powder showed the most superior anti-corrosive characteristics than other powders. 2. By anode polarization toward the noble direction from corrosion potential, corrosion current density with sprayed brake disc by Al-bronze powder was the lowest. 3. Mean frictional coefficients obtained from dynamo test are as follows : the sprayed disc with Al(99.99%) powder was 0.190 ; the sprayed disc with Al-bronze powder was 0.312 ; the sprayed disc with Mo powder was 0.257 ; the non-sprayed disc of gray cast iron was 0.331. In the case of the sprayed disc Al-bronze powder showed the most excellent frictional characteristics . 4. Amount of burnish quantity obtained from burnish test by dynamometer is as follows : the sprayed disc with Al-powder was 1.079 mm : the sprayed disc with Al-bronze powder was 0.155 mm : the sprayed disc with Mo powder was 0.253 mm : the non-sprayed disc of gray cast iron was 0.241 mm. Al-bronze powder also showed the most excellent burnish characteristics.

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Fabrication of Mo based Thermal Spray Composite Powder by Self- propagating High- temperature Synthesis (SHS 합성에 의한 몰리브덴계 용사용 복합분말의 제조)

  • Park, Je-Sin;Sim, Geon-Ju
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.763-768
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    • 2001
  • Molybdenum-based thermal spray powder is widely used for coating the moving parts of the internal combustion engines due to its excellent wear resistance. A composite powder of the $Mo_{40}(Al_{1-x}Si_x)_{60}$ system was synthesized using the SHS method. The synthesized bulk was pulverized and specially treated to produce thermal spray powder. It was found that the synthesis reaction consisted of two-steps: the formation of $Al_8/Mo_3$ and the formation of Mo(Al,Si)$_2$. Both the temperature and the rate of the SHS reaction linearly increased with the increase of the value of x in $Mo_{40}(Al_{1-x}Si_x)_{60}$, The temperature and the rate of the reaction were also affected by the compacting density of the specimens, exhibiting the maximum valves at 62% and 60%, respectively. Since spherical shape is advantageous to the thermal spraying process, shape-control of the powder was attempted with PVA as a binding additive, resulting in the successful production of almost perfectly spherical powder of 80 $\mu\textrm{m}$ Ø$(d_{50})$ mean particle size.

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Improvement of Powder Feeding Characteristics of Fine$5\mu\textrm{m}$ $Al_2O_3$ Powder by Modification of the Powder Feeding Systems and Characterization of the Coating Layer depending on Plasma Spraying Conditions (분말송급장치의 개조에 의한 미세$5\mu\textrm{m}$ $Al_2O_3$분말의 송급 특성개선 및 플라즈마 용사조건에 따른 코팅층의 특성분석)

  • 설동욱;김병희;정민석;임영우;서동수
    • Journal of Welding and Joining
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    • v.15 no.1
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    • pp.116-124
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    • 1997
  • A scope of this study is to establish the optimum plasma spray conditions for fine ($5\mu\textrm{m}$) $Al_2O_3$ powder. However, the flowability of the $Al_2O_3$ powder is not so good because of irregular particle shape and fine particle size. Therefore, powder feeding system was modified by 1) change of powder feeding line material from polymer to copper 2) shorten the powder feeding tube length 3) heating the powder feeding system to $80^{\circ}C$4) vibrating the powder feeding line continuously, in order to feed the fine powder homogeneously. The homogeneous powder feeding conditions were obtained with the modified powder feeding system by controlling the powder carrier gas flow and the powder flow rate indicator. The best plasma spraying conditions for the fine $Al_2O_3$ powder were found out as 40kw gun power, 80 g/min. powder feed rate and 50 mm working distance after characterizing the microstructure, hardness and wear loss of the $Al_2O_3$ coating layer.

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Effect of Process Parameters on the Morphology and Size of Spray-Dried Granule Powder for Fabrication of SiAlON Raw Material (SiAlON 원료분말제조를 위한 분무건조 과립분말의 형상과 크기에 미치는 공정변수효과)

  • Choi, Jae-Hyeong;Lee, Soyul;Han, Yoonsoo;Lee, Sung-Min;Nahm, Sahn;Kim, Seongwon
    • Korean Journal of Materials Research
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    • v.27 no.12
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    • pp.716-721
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    • 2017
  • SiAlON-based ceramics are some of the most typical ceramic materials used as cutting tools for HRSA(Heat Resistant Super-Alloys). SiAlON can be fabricated using ceramic processing, such as mixing, granulation, compaction, and sintering. Spray drying is a widely-used method for producing a granular powder of controlled morphology and size with flowability. In this study, we report a systematic investigation aimed at optimizing spherical granule morphology by controlling spray-drying parameters such as gas flow and feed rate. Before spray drying, the viscosities of the raw material slurries were also optimized with the amount of dispersant added.

Preparation of Al-SiCp Composite Coating by Plasma Thermal Spray (플라즈마 용사에 의한 Al-SiCp 복합재료 코팅층의 제조)

  • 민준원;유승을;김영정;김정석;서동수
    • Journal of the Korean Ceramic Society
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    • v.40 no.5
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    • pp.460-467
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    • 2003
  • Al-SiC$_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis.

NiAl Behavior at Plasma Spray Deposition

  • Orban, Radu L.;Lucaci, Mariana;Rosso, Mario;Grande, Marco Actis
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.692-693
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    • 2006
  • Behavior of stoichiometric and near-stoichiometric NiAl at plasma spray deposition, without and with a bond coat, for coating layers realization on a low alloyed steel substrate, has been investigated. In all variants, NiAl particle melting and subsequent welding at the impact with substrate were observed, forming a relatively compact and adherent coating layer with the NiAl stability maintaining - all assuring the coating layer oxidation and corrosion resistance. Good results from these points of view, also validated through corrosion tests, were obtained for 45:55 Ni:Al composition without a bond coat but adopting an Ar protective surrounding of plasma jet.

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