热反应扩散时间对钒铬共渗层显微形貌及性能的影响
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摘要
近年来,铬钒共渗层由于具有优良的综合性能被逐渐关注并广泛研究与应用,但已有的报道对其显微形貌尤其是界面结构以及性能的研究较少。采用热反应扩散法对Cr12钢进行铬钒共渗处理,利用光学显微镜(OM)、扫描电镜(SEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)对渗层的显微结构进行了分析。重点讨论了热反应扩散时间对渗层厚度、显微硬度、物相组成以及膜基结合力的影响;分析了主要元素沿渗层到基体方向的变化趋势和特点。结果表明:随着渗入时间的延长,所得渗层的厚度为2.0~8.2μm,渗层连续、均匀较致密。铬钒共渗层的物相组成主要为VC、Cr7C3和(Cr,Fe)7C3,反应过程中各物相对应的衍射峰强度会发生相应的变化。渗层的显微硬度值为1 683.80HV0.3~1 948.57HV0.3,明显高于空白基体的显微硬度值;划痕测试结果表明铬钒共渗层和基体的界面结合良好,结合力为55~64N。
In recent years,the chromium and vanadium carbide coating has been paid much attention and investigated as well as applied widely due to its excellent comprehensive properties.Unfortunately,there is not much data available about the microstructure,especially for the interface microstructure,and properties in the published literatures.In this study,the chromium and vanadium carbide coatings were successfully prepared on the Cr12 steel by thermo-reaction diffusion process.The microstructure of the as-obtained coatings was characterized by means of optical microscopy(OM),scanning electron microscopy(SEM),X-ray energy dispersive spectroscopy(EDS),X-ray diffraction analysis(XRD).Much more attention was paid on the influence of treatment time on the coating thickness,micro-hardness,phase constitute as well as bonding force of the coating and substrate.The evolution characters of the main elements from the coating surface to the interior of the substrate were discussed in detail.The results showed that the coating thickness was in the range of 2.0-8.2μm,depending on the duration.The as-received coatings are uniform,homogeneous and relatively dense.The X-ray studies showed that the chromium and vanadium carbide coatings mainly composed of VC,Cr7C3and(Cr,Fe)7C3.During the process,the intensity of the diffraction peaks for each phases varied accordingly.The microhardness of the as-produced coatings ranged from 1 683.80HV0.3to 1 948.57HV0.3 when the duration was 6h,which is much higher than the uncoated substrate.The scratch test indicated that the excellent bonding strength has been achieved between the as-fabricated coatings and the ferrous substrate,the bonding force ranged from 55 Nto 64N.
In recent years,the chromium and vanadium carbide coating has been paid much attention and investigated as well as applied widely due to its excellent comprehensive properties.Unfortunately,there is not much data available about the microstructure,especially for the interface microstructure,and properties in the published literatures.In this study,the chromium and vanadium carbide coatings were successfully prepared on the Cr12 steel by thermo-reaction diffusion process.The microstructure of the as-obtained coatings was characterized by means of optical microscopy(OM),scanning electron microscopy(SEM),X-ray energy dispersive spectroscopy(EDS),X-ray diffraction analysis(XRD).Much more attention was paid on the influence of treatment time on the coating thickness,micro-hardness,phase constitute as well as bonding force of the coating and substrate.The evolution characters of the main elements from the coating surface to the interior of the substrate were discussed in detail.The results showed that the coating thickness was in the range of 2.0-8.2μm,depending on the duration.The as-received coatings are uniform,homogeneous and relatively dense.The X-ray studies showed that the chromium and vanadium carbide coatings mainly composed of VC,Cr7C3and(Cr,Fe)7C3.During the process,the intensity of the diffraction peaks for each phases varied accordingly.The microhardness of the as-produced coatings ranged from 1 683.80HV0.3to 1 948.57HV0.3 when the duration was 6h,which is much higher than the uncoated substrate.The scratch test indicated that the excellent bonding strength has been achieved between the as-fabricated coatings and the ferrous substrate,the bonding force ranged from 55 Nto 64N.
引文
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2 Dejun K,Jinchun W,Haoyuan G.XPS and EDS analysis of VC coatings prepared by TD process[J].Rare Metal Mater Eng,2016,45(2):297.
3 刘秀娟,王华昌.不同基体材料TD法盐浴渗钒层的组织及硬度[J].材料热处理学报,2010(1):150.
4 孔德军,周朝政,吴永忠.TD处理制备VC涂层-基体元素扩散与界面特征[J].材料热处理学报,2012,33(8):140.
5 Aghaie-Khafri M,Fazlalipour F.Kinetics of V(N,C)coating produced by a duplex surface treatment[J].Surf Coat Technol,2008,202(17):4107.
6 Yuan Z,Wang Z,Zhang W,et al.Preparation and property of chromium carbide thermal diffusion coating on cold working die materials[J].J Wuhan University of Technology:Mater Sci Ed,2010,25(4):596.
7 Biesuz M,Sglavo V M.Chromium and vanadium carbide and nitride coatings obtained by TRD techniques on UNI42CrMoS4(AISI 4140)steel[J].Surf Coat Technol,2016,286:319.
8 Ghadi A,Soltanieh M,Saghafian H,et al.Investigation of chromium and vanadium carbide composite coatings on CK45steel by thermal reactive diffusion[J].Surf Coat Technol,2016,289:1.
9 黄福祥,姜智枭,曹登驹,等.模具铬钒稀土多元共渗层组织及腐蚀性能研究[J].重庆理工大学学报:自然科学版,2015,29(4):48.
10 Fan X S,Yang Z G,Zhang C,et al.Thermo-reactive deposition processed vanadium carbide coating:Growth kinetics model and diffusion mechanism[J].Surf Coat Technol,2012,208:80.
11 Kong D,Dan L,Wu Y,et al.Mechanical properties of hydroxyapatite-zirconia coatings prepared by magnetron sputtering[J].Trans Nonferrous Metals Soc China,2012,22(1):104.
12 Hogmark S,Jacobson S,Larsson M.Design and evaluation of tribological coatings[J].Wear,2000,246(1):20.
13 Fenker M,Balzer M,Jehn H A,et al.Improvement of the corrosion resistance of hard wear resistant coatings by intermediate plasma etching or multilayered structure[J].Surf Coat Technol,2002,150(1):101.
14 Zhang S,Wang L,Wang Q,et al.A superhard CrAlSiN superlattice coating deposited by multi-arc ion plating:I.Microstructure and mechanical properties[J].Surf Coat Technol,2013,214:160.
15 Cai F,Zhang S,Li J,et al.Effect of nitrogen partial pressure on Al-Ti-N films deposited by arc ion plating[J].Appl Surf Sci,2011,258(5):1819.