Sen YANG
,
Wenjin LIU
,
Minlin ZHONG
,
null
,
null
材料科学技术（英）
A Ni-base alloy composite coating reinforced with TiC particles of various shapes and sizes on medium carbon steel substrate was produced by multilayer laser cladding. The chemical compositions, microstructures and surface morphology of the cladded layer were analyzed using energy dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), and X-ray diffractometry (XRD). The experimental results showed that an excellent metallurgical bonding between the coating and the substrate was obtained. The microstructure of the coating was mainly composed of γ-Ni dendrites, a small amount of CrB, Ni3B, M23C6 and dispersed TiC particles. Much more and larger TiC particles formed in the overlapping zone, which led to a slightly higher microhardness of this zone. The maximum microhardness of the coating was about HV0.21200. The effects of the laser processing parameters on the microstructures and properties of coating were also investigated.
关键词:
Laser cladding
,
null
,
null
,
null
Kaijin HUANG
材料科学技术（英）
The microstructure and wear behaviour of the thermite reaction coating produced by the hybrid laser cladding-remelting on AA7075 aluminum alloy for the systems of Al-CuO-SiO2, Al-Cr2O3-SiO2, Al-Fe2O3-SiO2, and Al-TiO2-SiO2 were studied. The results of the X-ray diffraction (XRD) analysis show that in all the four reaction coatings, α-Al2O3 and γ-Al2O3 phases were present at the top surface, together with various intermetallic phases, the corresponding reduced metal and Al phase in the fusion zone. Under the dry sliding condition, the wear resistance, in terms of weight loss, of the laser-clad specimens was considerably higher than that of the untreated specimen. The predominant wear mechanism of the former specimens was abrasive wear, while for the latter, it was the adhesive wear that prevailed.
关键词:
Laser cladding
,
cladding
,
thermite
,
reaction
,
aluminu
Matej Pleterski
材料科学技术（英）
Repair welding of cold-work tool steels in cold is very risky and almost impossible by conventional processes. The application of pulse shaping in laser cladding with wire to avoid the solidification problems in relevant steel is demonstrated. The results show that sound remelting and/or cladding can be achieved by the right selection of laser parameters and pulse shape, i.e. long pulse duration, moderate pulse peak powers and ramped-down
pulse shape. Despite the defects and softening in the cladding due to the formation of retained austenite, the cladding shows better wear resistance at lower loads compared to the heat-treated base material.
关键词:
Laser cladding
Yali GAO
,
Dangsheng XIONG
,
Cunshan WANG
,
Yongzhe CHEN
金属学报(英文版)
doi:10.1016/S1006-7191(08)60085-X
Al-Si alloy coatings were prepared on AZ91HP magnesium alloy by broad-beam laser cladding; the influences of the powers on the microstructure and properties of the coatings were discussed. It was found that the microstructure of the coatings at the powers of 3 and 3.5kW was characterized by Mg2Si dendrites, and needle-like Mg2Al3(hcp) dispersing in the Mg17Al12 matrix, whereas the coating at the power of 2.5 kW was composed of the petal-like Mg2Al3 (fcc) as well as the needle-like Mg2Al3(hcp). The coating at the power of 4 kW appeared as α-Mg solid solution and Mg2Si, Mg17Al12, as well as Mg2Al3 (hcp). The coatings with the powers of 3 and 3.5 kW exhibited higher microhardness and better wear resistance because of more Mg2Si and Mg17Al12. However, the coating at the power of 2.5 kW displayed better corrosion resistance.
关键词:
Magnesium alloy
,
null
,
null
,
null
杨垒
,
李文戈
材料科学与工艺
综合应用激光熔覆和原位反应增强金属基复合材料,是当前金属基复合材料研究领域的一个热点,本文采用该工艺制备铁基表面复合材料,重点考虑该工艺参数的确定问题.根据在不同工艺参数下合成的铁基表面的WC体积分数实测数据集,提出建立不同工艺参数下WC体积分数的支持向量回归预测模型,并与基于人工神经网络模型（ANN）的预测结果进行比较.结果显示：对于相同的训练样本和检验样本,SVR预测模型比ANN预测模型具有更强的泛化能力.最后根据建立的预测模型,应用粒子群算法寻优得到最优工艺参数,该工艺参数在实际实验过程中的应用,验证了该方法的有效性.
关键词:
激光熔覆
,
原位自生
,
支持向量回归
,
粒子群算法
