Papers by Keyword: Laser Cladding

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Authors: Yao Ning Sun, Ding Fan, Yu Feng Zheng, Min Zheng, Jian Bin Zhang
Abstract: Laser cladding technique was used to form Ni3Si intermetallic composite coating reinforced by in-situ formation NbC particles on Ni-based superalloy substrate. The process parameters were optimized to obtain cladding. The effect of Nb-C addition to the microstructure of the coating was investigated. The morphology of reinforcement particles was discussed. The experimental results showed that an excellent bonding between the coating and the substrate was ensured by a strong metallurgical interface. The clad coating was very good and free from cracks and pores. The microstructure of the coating was mainly composed of Ni(Si), Ni3(Si, Nb) and NbC. The NbC particles were formed by in-situ reaction between Nb and C during laser cladding process. NbC particles were homogeneously distributed in the composite material. Moreover, the maximum size of NbC particles was more than 4 μm.
Authors: Zhao Bing Cai, Xue Jia Pang, Xiu Fang Cui, Xin Wen, Zhe Liu, Mei Ling Dong, Yang Li, Guo Jin
Abstract: In order to improve the surface properties of Ti-6Al-4V, high-entropy alloy coatings were prepared by in-situ laser cladding on the surface of Ti-6Al-4V substrate. The microstructure, micro-hardness, corrosion resistance and wear resistance were investigated. The results showed that the high-entropy alloy coating was composed of BCC high-entropy alloy phase, α-Ti phase and (Ni, Co)Ti2 phase. The micro-hardness of the high-entropy alloy coatings is much higher than that of Ti-6Al-4V substrate. The coating also has a better corrosion resistance than Ti-6Al-4V substrate, even superior to 304SS in 3.5wt.% NaCl solution at room temperature. Compared with Ti-6Al-4V substrate, the high-entropy alloy coating has a greater wear resistance with the wear mass loss decreased 28.2% and 23.1%, respectively. Wear patterns of Ti-6Al-4V substrate and high-entropy alloy coatings are the coexistence of adhesive wear and abrasive wear, but the wear degree of high-entropy alloy coatings is lower.
Authors: Fang Zhou, Hui Yao Yang, Liang Hua He
Abstract: A Fe-based composite coating reinforced with in situ synthesized TiC-TiB2 particles was successfully fabricated on Q235A by laser cladding with mixture powder of TiO2, Al, B4C, C and Fe55 as precursors. The microstructure and mechanical properties of coating were investigated. The results show that the main phases of coating are TiB2, TiC, (Fe,Cr)7C3 and α-Fe. TiC particles show the shape of block, TiB2 particles exhibit the shape of strip. Compared with the Q235A, the microhardness of the composite coating improved drastically.
Authors: Xue Liu, Sen Yang
Abstract: To extend the mould cycle duration and to reduce cost, a TiB2 particulate reinforced Cu based composite coating was produced on hot-working die steel substrate using laser cladding. The experimental results showed that TiB2 particles embedded in copper based alloy were in-situ synthesized during laser processing. An excellent bonding between the coating and the substrate was obtained. The microstructure of the coating was mainly composed of -Cu dendrites and dispersed TiB2 particles. The maximum microhardness of the coating was about 800HV0.2. The wear resistance of the coating was evaluated under room temperature dry-sliding wear test condition. Due to the presence of a large amount of TiB2 particles, the composite coating exhibited excellent wear resistance compared with that of substrate.
Authors: Yu Ling Yang, Wei Yan, Duo Zhang, Gen Zong Song, Yi Ran Zheng
Abstract: The insitu-fabrication of TiCN ceramic coating by laser cladding-laser nitriding technique (LC-LN) was investigated. Pulsed YAG laser with the power of 500W was used as radiation source. Highly pure N2 was selected as the nitriding element; Titanium powder whose size is 20 m and the pure carbon powder were utilized as the coating materials. The influence of technology parameters such as pulse width, pulse frequency and scanning speed etc. on the insitu-formation of TiCN ceramic coating was studied. XRD results show that the main phases of the coating are TiC0.3N0.7 (or TiC0.2N0.8),TiN and TiN0.3. It was revealed that the appropriate process parameters for insitu-fabrication are the pulse frequency 15 Hz, pulse width 3.0ms, the scanning speed in the range of 9cm/min to 12cm/min, the pressure of N2 0.4MPa. The result of OM showed a metallurgical bonding without crack and bubble between the coating and the substrate was obtained. The microstructure of cladded coating is characterized by fine dentrites. The average microhardness in the coating is more than 1300HV which is about 4 times of that in the substrate.
Authors: Chi Sheng Chien, Yu Sheng Ko, Tsung Yuan Kuo, Tze Yuan Liao, Ting Fu Hong, Tzer Min Lee
Abstract: Hydroxyapatite (HA) is a frequently used bioactive coating material. However, when HA coating is soaked in the simulated body fluid (SBF), it is usually detached from substrate material due to its high dissolution rate in the solution. Recently, it is found that Fluorapatite (FA) has a better anti-dissolution ability than HA. In this study, Fluorapatite was mixed with TiO2 powder (either Anatase phase (A) or Rutile phase (R)) as a coating material precursor, and then be deposited on Ti-6Al-4V substrate to form the coating layer by using Nd-YAG laser cladding process. After soaking in SBF for various days, it is observed that dense ball-like apatite grew faster on the surface of the FA+R coating layer than that on the surface of the FA+A specimens. The corresponding Ca/P ratios of FA+R specimens also dropped faster than FA+A ones.
Authors: Alexandru Pascu, Iosif Hulka, Mircea Horia Tierean, Catalin Croitoru, Elena Manuela Stanciu, Ionut Claudiu Roată
Abstract: This paper addresses to the characterization of Ni based coatings realized by two different processes e.g. thermal spray coating and laser cladding. For the relevance of the experimental tests, the same base material, AISI 5140 and Metco 15E powder was used. The results highlight the advantages and disadvantages of the both techniques. The cladded layer obtained through laser cladding is pore and crack free, being characterized by a high hardness and a very good adherence to the substrate, while the flame coating presents oxides inclusions, high porosity, lower hardness and minimal dilution with the substrate as resulted from the EDS analyses. In depth characterization of the samples is made using optical and scanning electron microscopy, EDS analysis and microhardness testing.
Authors: Fei Wang, Xi Chen Yang
Abstract: The powder feeder head is studied, which is one of the key to laser cladding. In view of many coaxial nozzles that are used nowadays, we have found that while cladding is doing, most of the nozzles have poor affect on powder-gathering. So as have researched on the theoretical and experiments, we designed a new coaxial nozzle, which has a great affect on powder-gathering, and can be modular disassembled. We have researched on powder stream theoretically, shot the morphology of powder stream by using high-resolution CCD camera, and analyzed the parameters of powder stream. And this new coaxial nozzle has been used in laser cladding experiments.
Authors: Lino Costa, Imre Felde, Tamás Réti, Zoltán Kálazi, Rogerio Colaço, Rui Vilar, Balázs Verő
Authors: Shu Fa Chen, Cheng Long Feng, Jin Yang, Jin Song Chen
Abstract: NiCr/Cr3C2-WS2-CaF2 mixed powders were prepared on 1Cr18Ni9Ti stainless steel substrate to fabricate high-temperature self-lubrication wear resistant composite coating by laser cladding. The microstructure of the coating was examined by means of XRD, SEM and EDS. The high-temperature dry sliding friction and wear behavior of the composite coating were evaluated by using a ball-on-block wear tester at room temperature, 300 and 600 , respectively. The results showed that the composite coating had a unique microstructure consisting of γ-(Ni,Fe) solid solution matrix, Cr7C3/WC reinforcement and CrS/WS2 lubricant particles. The hardness of NiCr/Cr3C2-WS2-CaF2 coating by laser cladding was lower than NiCr/Cr3C2 coating, but higher than stainless steel substrate significantly. It was because of the addition of solid lubricant. In the wear process, elevated temperature was helpful to form a lubricating transfer film. As a result, the NiCr/Cr3C2-WS2-CaF2 coating exhibited a notable anti-friction and wear resistance at 300 and 600 .
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