• Title/Summary/Keyword: HVOF

Search Result 101, Processing Time 0.031 seconds

The Micro Structure Characteristics of Coating Layer on SM490B with HVOF Coating (HVOF용사 코팅한 SM490B 코팅층의 미시조직 특성)

  • Nam Ki-Soo;Cho Won-ik;Yoon Myung-Jin;Kim Byung-Moon
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.14 no.5
    • /
    • pp.80-86
    • /
    • 2005
  • High velocity oxy-fuel thermally sprayed coating of the WC-Co cermet material is a well-established process for modifying the surface properties of the structural components exposed to the corrosive and wear attacks. The hard WC phase in the coating resists to the wear while the soft metallic Co increases the adhesive and cohesive bonding properties. The coating properties deposited by the HVOF process are greatly dependent on the feedstock materials and processing parameters. The effects of the feedstock material and process coating parameters including the in-flight particle parameters and resultant coating microstructures were observed in this paper.

Tribological Behaviors of Chromium Carbide Coatings by HVOF Thermal Spraying (HVOF 열용사에 의한 크롬 카바이드 코팅의 마모.마찰거동)

  • 김장엽;임대순;이상로;변응선;이구현
    • Journal of the Korean Ceramic Society
    • /
    • v.32 no.11
    • /
    • pp.1315-1321
    • /
    • 1995
  • The optimal coating condition for chrominum carbide coating was selected by Taguchi method. The wear tests with coated specimens by HVOF method were performed in the temperature to 80$0^{\circ}C$. Applied normal loads were selected to be from 8N to 30N. The worn surfaces and subsurfaces were characterized by XRD, EPMA, AES and SEM. The wear track increased with increasing applied normal load, and in terms of the temperature range from 400 to $600^{\circ}C$, below that range, the wear track increased, and above that temperature ragne, the wear track decreased. The degree of oxidation caused by the test temperature and the frictional heating was responsible to the unique high temperature wear behavior chromium carbide coatings.

  • PDF

The influence of spraying conditions to the coating layer properties of Fe-Cr-Ni-Mo-Si-B alloy using the HVOF (HVOF를 이용한 Fe-Cr-Ni-Mo-Si-B계 고성능 합금 용사층의 특성에 미치는 용사조건의 영향)

  • 권기봉;조대형;장영권;백영남
    • Journal of the Korean institute of surface engineering
    • /
    • v.35 no.1
    • /
    • pp.5-10
    • /
    • 2002
  • This study was performed to investigate the influence of spraying condition to the coating layer properties of Fe-Cr-Ni-Mo-Si-B alloy using the HVOF. The investigations, such as thickness measurement, surface roughness, hardness, friction coefficient, resistance of corrosion were carried out. Matrix is prepared by gritting and coating layer is made of Fe-Cr-Ni-Mo-Si-B alloy powder using HVOF. Alumina gritting layers are superior to steel gritting layers. The less spaying distance, the more coating layer properties confirmed. The optimum spraying condition, in this study, was proved as 13inch spraying distance with feed rate 350rpm (78g/min).

Anti-Corrosion Characteristics of WC-based Alloy Coatings Fabricated by HVOF Process - Polarization Characteristics in Alkaline Solution - (HVOF 용사법에 의해 제조된 WC계 합금 코팅층의 방식특성(II) - 알칼리 용액에서의 분극특성 -)

  • Kim, Tae-Yong;Kim, Yeong-Sik;Kim, Jae-Dong
    • Journal of Power System Engineering
    • /
    • v.18 no.6
    • /
    • pp.40-44
    • /
    • 2014
  • The purpose of this paper is to investigate polarization characteristics of WC-based alloy coatings in alkaline solution. The coatings were fabricated with WC-CrC-Ni, WC-Co-Cr and WC-Co composite powders by HVOF process. Corrosion tests of coatings and substrate were carried out using potentiostat/galvanostat at solution with pH 8 and pH 13. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be studied from polarization curve, and corrosion behavior was analyzed by SEM and EDS. WC-Co-Cr coating and WC-CrC-Ni coating showed more favorable anti-corrosion characteristics than WC-Co coating and substrate at solution with pH 8 and pH 13.

Preparation of gas-atomized Fe-based alloy powders and HVOF sprayed coatings

  • Chau, Joseph Lik Hang;Pan, Alfred I-Tsung;Yang, Chih-Chao
    • Advances in materials Research
    • /
    • v.6 no.4
    • /
    • pp.343-348
    • /
    • 2017
  • High-pressure gas atomization was employed to prepare the Fe-based $Fe_{50}Cr_{24}Mo_{21}Si_2B_3$ alloy powder. The effect of flow rate of atomizing gas on the median powder diameter was studied. The results show that the powder size decreased with increasing the flow rate of atomizing gas. Fe-based alloy coatings with amorphous phase fraction was then prepared by high velocity oxygen fuel spraying (HVOF) of gas atomized $Fe_{50}Cr_{24}Mo_{21}Si_2B_3$ powder. Microstructural studies show that the coatings present dense layered structure and low porosity of 0.17% in about $200{\mu}m$ thickness. The Fe-based alloy coating exhibits an average hardness of about 1230 HV. Our results show that the HVOF process results in dense and well-bonded coatings, making it attractive for protective coatings applications.

HVOF Thermal Spray Coating of WC-Co for Durability Improvement of High Speed Spindle (초고속 스핀들의 내구성 향상을 위한 WC-Co 분말의 HVOF 용사 코팅)

  • Kim, K.S.;Baek, N.K.;Yoon, J.H.;Cho, T.Y.;Youn, S.J.;Oh, S.K.;Hwang, S.Y.;Chun, H.G.
    • Journal of the Korean institute of surface engineering
    • /
    • v.39 no.4
    • /
    • pp.179-189
    • /
    • 2006
  • High velocity oxygen fuel(HVOF) thermal spray coating of WC-Co powder is one of the most promising candidate for the replacement of the traditional hard chrome plating and ceramics coating because of the environmental problem of the very toxic $Cr^{6+}$ known as carcinogen and the brittleness of ceramics coating. WC-Co micron and nano powder were coated by HVOF thermal spraying method for the study of durability improvement of the high speed spindle. Coatings were planned by Taguchi program for the four spray parameters of spray distance, flow rates of hydrogen, oxygen and powder feed rate. Optimal coating process was obtained by the studies of coating properties such as porosity, surface roughness, micro hardness, and micro structure. WC-Co micron and nano powder were coated on the Inconel 718 substrate by the optimal coating process obtained in this study. The wear behaviors were studied by the sliding wear tester at room temperature and at an elevated temperature of $500^{\circ}C$ for the application to high speed spindle. Sliding wear test was carried out for four most promising hard coatings of chrome coating, ceramics coatings such as $A1_2O_3,\;Cr_2O_3$ and HVOF Co-alloy T800 for the comparison of their wear behaviors. HVOF WC-Co coating was better than other coatings showing highest micro hardness of 1400 Hv and comparable friction coefficients with others. HVOF WC-Co coating is a strong candidate for the replacement of the traditional hard chrome plating for the high speed spindle.