scholarly journals Geometric Influence of Hard Phase on Corrosion Performance between WC-Reinforced Coatings Prepared by High-Velocity Oxygen-Fuel Spray and Electric Contact Strengthening

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 694
Author(s):  
Ze Sun ◽  
Shigen Zhu ◽  
Weiwei Dong ◽  
Hao Ding ◽  
Yunfeng Bai ◽  
...  
Keyword(s):  
High Velocity ◽  
Spherical Geometry ◽  
Element Distribution ◽  
Open Circuit ◽  
Fuel Spray ◽  
High Velocity Oxygen Fuel ◽  
Electric Contact ◽  
Hard Phase ◽  
Lower Porosity ◽  
Oxygen Fuel

Several kinds of WC-reinforced coatings were prepared by high-velocity oxygen-fuel spray (HVOF) and electric contact strengthening (ECS), respectively, and their corrosion behaviors in 3.5% NaCl solution were investigated. The microstructure, element distribution, phase and corrosion resistance of these coatings were compared. The results showed that, compared with HVOF-sprayed coatings, the ECS-prepared coatings were denser and with lower porosity. Simultaneously, the ECS coatings that used raw powder commercial WC-12Co retained the original spherical geometry of the hard phase. In open-circuit potential measurements, these ECS coatings gave higher stable potentials (Eocp). In potentiodynamic polarization tests, although the corrosion currents (icorr) of the homogeneous coatings were approximately the same, these ECS coatings still exhibited higher corrosion potentials (Ecorr). The spherical geometric distribution of the hard phase led to a bounded diffusion model caused by the diffusion change of corrosion products.

Difference oxidation behaviors of Ni8Al and Ni25Cr coatings in air with water vapor at 650∘

2021 ◽  
pp. 2150274
Author(s):  
Dingjun Li ◽  
Wenlang Huang ◽  
Xiaohu Yuan ◽  
Taihong Huang ◽  
Chao Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Velocity ◽  
Cyclic Oxidation ◽  
Oxidation Behaviour ◽  
Fuel Spray ◽  
High Velocity Oxygen Fuel ◽  
Service Environment ◽  
Generator Unit ◽  
Oxygen Fuel ◽  
Oxidation Behaviors

The oxidation behaviour of Ni8Al and Ni25Cr coatings produced by high velocity oxygen fuel spray (HVOF) which were deposited on Fe-based alloys (CB2) was investigated. We simulated the service environment of the steam generator unit, and put the samples in a thermostatic tube furnace at 650[Formula: see text] in air with 20 wt.% water vapor for 1000 hours of cyclic oxidation. The formation mechanism are explained using SEM, XRD, and EDX. There were no spallations and obvious cracks in both coatings. Ni25Cr coating generated a better protection oxides scale than that scale on Ni8Al. The behavior and mechanism of the oxide scale formation had an important influence in coatings and we have discussed these phenomenons in the study.

Experimental study on the erosion behavior of WC-based high-velocity oxygen-fuel spray coating

2017 ◽  
Vol 318 ◽  
pp. 383-389 ◽  
Author(s):  
Chao Zheng ◽  
Yonghong Liu ◽  
Jie Qin ◽  
Wenxuan Ji ◽  
Shihong Zhang ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Velocity ◽  
Spray Coating ◽  
Fuel Spray ◽  
High Velocity Oxygen Fuel ◽  
Erosion Behavior ◽  
Oxygen Fuel

Multi-objective optimization of WC-12Co coating by high-velocity oxygen fuel spray using multiple regression-based weighted signal-to-noise ratio

2021 ◽  
pp. 095440542097666
Author(s):  
Thanh-Phu Nguyen ◽  
Thanh-Hoa Doan ◽  
Van-Canh Tong
Keyword(s):  
Multiple Regression ◽  
Adhesion Strength ◽  
High Velocity ◽  
Signal To Noise Ratio ◽  
Fuel Spray ◽  
Spray Parameters ◽  
High Velocity Oxygen Fuel ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Oxygen Fuel

In this study, the optimal process parameters for a high-velocity oxygen fuel spray, which was used to deposit WC-12Co coating on a 16Mn steel substrate, were studied to simultaneously improve the microhardness, adhesion strength, and porosity of the coating. To this end, trial tests were conducted to determine the feasible ranges of the spray parameters: powder feed rate ( A), spray distance ( B), and oxygen/propane mixture ratio ( C). Taguchi orthogonal array (L9) experimental design was used to determine regression formulae for the microhardness, adhesion strength, and porosity. Then, based on a method using the multiple regression-based weighted signal-to-noise ratio, the optimal spray parameters were identified. To verify the optimization results, confirmation experiments were carried out. An analysis of variance was also conducted to check the proportion of contribution of the spray parameters on the output quality characteristics. The confirmation test results proved that the predicted and measured results were in good agreement. The optimal conditions of the high-velocity oxygen fuel spray were: A = 32 g/min, B = 0.35 m, and C = 5. The estimated optimal coating properties were: microhardness = 1335.784 HV, adhesion strength = 64.659 MPa, and porosity = 1.797%. The oxygen/propane ratio showed the highest contribution to the microhardness, whereas the most influential factor for both adhesion strength and porosity was the spraying distance.

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