Laser cladding composite coatings by Ni–Cr–Ti–B₄C with different process parameters

ABSTRACT

To investigate the effect of laser process parameters on microstructure and properties of composite coating, the composite coatings were manufactured by laser cladding Ni–Cr–Ti–B₄C mixed powder on Q235 mild steel with different process parameters. The coatings are bonded with the substrate by remarkable metallurgical binding without cracks and pores. The composite coatings are consisted of in situ synthesized solid solution Ni–Cr–Fe, intermetallic compound (IMC) Ni₃Ti, Cr₂Ti, and ceramic reinforcements TiB₂, TiC. Results of scanning electron microscopy (SEM) revealed that the ceramic reinforcements became coarser with higher specific energy (E_s). There were independent ceramics TiB₂, TiC, eutectic ceramic TiB₂–TiC in coatings, and eutectic alloy–ceramic was detected. Compared with the substrate, the microhardness of coatings was increased significantly, and the maximum microhardness of coatings was approximately five times as high as the substrate. The wear resistance of coatings was improved dramatically than the substrate. Compared to the coatings with lower E_s, higher E_s led to lower microhardness and worse wear resistance ascribing to more Fe diffused into the coating from the substrate.

KEYWORDS:

• Laser
• cladding
• composite
• coatings
• parameters
• ceramic
• reinforcements
• microstructure
• hardness
• wear
• resistance

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study work was supported by the National Natural Science Foundation of China: [Grant Number 51475232], Young Scientists Fund of the National Natural Science Foundation of China: [Grant Number 51605473], Jiangsu Provincial Research Foundation for Basic Research: [Grant Number BK20161476], and Science and Technology Planning Project of Jiangsu Province of China: [Grant Number BE2015029].