Preparation And Study On Properties Of Antiscale, Anticorrosion And Antiwear Coatings

In order to solve scaling and corrosion phenomena of oilfield equipment, the experiment choose Al2O3-13%TiO2 and Cr3C2-NiCr powder,La2O3 as additive.La2O3 were added to raw materials as two kinds of composite powder, the percentage of which is 3wt%,6wt% and 9wt%.The Al2O3-13%TiO2 and Cr3C2-NiCr ceramic coatings are prepared by plasma spraying equipment, micro structure and properties of coatings are studied. Interface stress of coatings is calculated with ANSYS software Results of calculation indicate that Al2O3-13%TiO2 and Cr3C2-NiCr coatings of single structure have the same rule of residual stress distribution. Speed of spraying particle arriving at surface of coatings and substrate affects the impact of residual stress distribution.Transition layer addition of Al2O3-13%TiO2 coating can significantly reduce its interface stress. But when parameter of substrate and Cr3C2-NiCr coating is not different, influence of transition layer is not obvious.Research results of micro structure and properties of coatings show that in the condition of the experiment, micro structure density, micro-hardness, binding strength, contact angle, anti-corrosion and anti-wear of Cr3C2-NiCr coating is greater than which of Al2O3-13%TiO2 coating. Low surface energy of NiCr-Cr3C2 coating causes induction growth and adhesion reduction of scale, its anti-scaling performance is superior to Al2O3-13%TiO2 coating. In the condition of the experiment, rare earth mixed into Al2O3-13%TiO2 and Cr3C2-NiCr coating, when addition of rare earth is less than 6%, microstructure density, micro-hardness, binding strength and contact angle of two kinds of coatings increases with addition of rare earth increasing, surface energy, corrosion current, scale weight increment, erosion weight loss reduce with addition of rare earth increasing; when addition of rare earth is more than 6%, microstructure of two kinds of coatings deteriorate, micro-hardness, binding strength and contact angle present the trend of reducing, surface energy, corrosion current, scale weight increment and erosion weight loss present the trend of increasing. When addition of rare earth is 6%, undense defects, coarse grains, asymmetric defects are improved, anti-scale and anti-corrosion and anti-wear of coatings are optimalizing. Scaling mechanism of coating is that when the concentration of produced water is saturated, MPCs of ion or molecule of solution generates crystal nucleus, alternative grows to crystals, which separate out and form to scale. Initiation and propagation of cracks and delamination spallings is the main corrosion failure mechanism. Erosion mechanism is layer strip resulted from interlaminar and particles weak bonding zones.