scholarly journals The Effects of the Addition of Ti3SiC2 on the Microstructure and Properties of Laser Cladding Composite Coatings

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 498 ◽  
Author(s):  
Qin Shi ◽  
Hejun Zhu ◽  
Changsheng Li

This study explored the effects of Ti3SiC2 on the microstructure and properties of laser cladding coatings using X-ray diffractometer, scanning electron microscope, electrochemical workstation, and UMT-2 wear tester analyses. It was found that with the addition of Ti3SiC2, the reinforcing phases in the composite coating were TiC, Ti(B,C)2, honeycomb-like (Cr, Fe)23C6, and a novel composite ceramic with an “eyeball” structure, which had an inside core of Al2O3 and TiC outer surrounding structure. The microhardness, wear, and corrosion resistance of the composite coating were about 1.35, 2, and 4.3 times those of the original coating, respectively. The main wear mechanisms of the original coating were severe fatigue spalling and microcutting, while the main mechanisms of the composite coating were slight microcutting and the formation of the transferred film.

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 684 ◽  
Author(s):  
Jianfeng Li ◽  
Zhencai Zhu ◽  
Yuxing Peng ◽  
Gang Shen

In this study, the effect of carbon fibers (CFs) on the microstructure and wear resistance of Fe-based alloy coating produced by laser cladding was investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), and wear tester. The results indicated that with the addition of CFs, the microstructure of the composite coating mainly transformed from α-Fe cellular dendrites and γ-Fe/(Cr, Fe)7C3/CrB eutectics to bulk-like (Cr, Fe)7C3, nano-size B4C, and γ-(Fe, Ni)/(Cr, Fe)23C6 lamellar eutectics. Additionally, the microhardness and wear resistance of the composite coating compared with the original coating both increased by approximately two times. The original coating showed the dominant wear mechanisms of micro-cutting and serious brittle spalling, while the composite coating with CFs showed the main wear mechanism of slight scratching.


2011 ◽  
Vol 311-313 ◽  
pp. 344-347
Author(s):  
Qian Wang

Compared with ordinary coatings, nano-composite coating usually has a higher hardness and better wear and corrosion resistance. As coating materials, the nano-CeO2/Zn composites were prepared by nano-CeO2 and Zn powder. The microstructure was investigated by XRD and FESEM. The corrosion resistance and hardness of nano-CeO2/Zn composites with different amount of nano-CeO2 were comparatively studied. The results show that the metal corrosion resistance, hardness and density of the composites may be improved significantly by addition of nano-CeO2, and the optimal amount of nano-CeO2 is 1%.


Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 843
Author(s):  
Sipiwe Trinity Nyadongo ◽  
Sisa Lesley Pityana ◽  
Eyitayo Olatunde Olakanmi

It is anticipated that laser cladding assisted with preheat (LCAP)-deposited Tribaloy (T-800) composite coatings enhances resistance to structural degradation upon exposure to elevated-temperature oxidation service environments. The oxidation kinetics of LCAP T-800 composite coatings deposited on EN8 substrate and its mechanisms have not been explored in severe conditions that are similar to operational parameters. The isothermal oxidation behaviour of the T-800 composite coating deposited on EN8 via LCAP was studied at 800 °C in air for up to 120 h (5 × 24 h cycles) and contrasted to that of uncoated samples. The mass gain per unit area of the coating was eight times less than that of the uncoated EN8 substrate. The parabolic rate constant (Kp) for EN8 was 6.72 × 10−12 g2·cm−4·s−1, whilst that for the T-800 composite coating was 8.1 × 10−13 g2·cm−4·s−1. This was attributed to a stable chromium oxide (Cr2O3) layer that formed on the coating surface, thereby preventing further oxidation, whilst the iron oxide film that formed on the EN8 substrate allowed the permeation of the oxygen ions into the oxide. The iron oxide (Fe2O3) film that developed on EN8 spalled, as evidenced by the cracking of oxide when the oxidation time was greater than 72 h, whilst the Cr2O3 film maintained its integrity up to 120 h. A parabolic law was observed by the T-800 composite coating, whilst a paralinear law was reported for EN8 at 800 °C up to 120 h. This coating can be used in turbine parts where temperatures are <800 °C.


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