The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were i...The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were investigated. The electrochemical results show that corrosion resistance of coatings in static acid solutions is higher than that in cavitation ones. In each case, coating corrosion resistance in descending order is in nitric, sulfuric and hydrochloric acid solutions. Obvious erosion-corrosion morphology and serious intercrystalline corrosion of coating are noticed in cavitation hydrochloric acid solution. This is mainly ascribed to the aggressive ions in hydrochloric acid solution and mechanical effect from cavitation bubbles collapse. While coating after corrosion test in cavitation nitric acid solution shows nearly unchanged surface morphology. The results indicate that the associated action of cavitation and property of acid solution determines the corrosion development of coating. Hastelloy C22 coating exhibits better corrosion resistance in oxidizing acid solution for the stable formation of dense oxide film on the surface.展开更多
Cavitation tests of hydraulic model were carried out in vacuum tank. A classical theory for cavitation tests in vacuum tank has been used. According to two principles, the test procedure in vacuum tank and the predict...Cavitation tests of hydraulic model were carried out in vacuum tank. A classical theory for cavitation tests in vacuum tank has been used. According to two principles, the test procedure in vacuum tank and the prediction of cavitation features on prototype were obtained. However, by using these test results it can not make a reliable prediction of cavitation feature on prototype. It shows what should be the considerable reasons for the difficulties in comparison between the results of cavitation tests in vacuum tank and how to improve the cavitation tests under a condition of vacuum pressure.展开更多
This paper is mainly devoted to conduct a series of vibratory cavitation erosion tests using the magnetostriction apparatus. Distilled water was used as a standard liquid medium for comparison and other liquids were g...This paper is mainly devoted to conduct a series of vibratory cavitation erosion tests using the magnetostriction apparatus. Distilled water was used as a standard liquid medium for comparison and other liquids were glycerine, kerosene, silicone oil and water containing different concentration glycerine and solid particles, bakerite and fly ash. Experimental results indicate that viscosity of liquid restrains, attenuates and alleviats cavitation erosion. Experiments witness that there exists critical concentration and equivalent concentration. The behaviour of cavitation clouds and the appearance of the pitting were observed. It is helpful to explain the effect of liquid quality on cavitation erosion.展开更多
文摘The Hastelloy C22 coatings on Q235 steel substrate were produced by high power diode laser cladding technique. Their corrosion behaviors in static and cavitation hydrochloric, sulfuric and nitric acid solutions were investigated. The electrochemical results show that corrosion resistance of coatings in static acid solutions is higher than that in cavitation ones. In each case, coating corrosion resistance in descending order is in nitric, sulfuric and hydrochloric acid solutions. Obvious erosion-corrosion morphology and serious intercrystalline corrosion of coating are noticed in cavitation hydrochloric acid solution. This is mainly ascribed to the aggressive ions in hydrochloric acid solution and mechanical effect from cavitation bubbles collapse. While coating after corrosion test in cavitation nitric acid solution shows nearly unchanged surface morphology. The results indicate that the associated action of cavitation and property of acid solution determines the corrosion development of coating. Hastelloy C22 coating exhibits better corrosion resistance in oxidizing acid solution for the stable formation of dense oxide film on the surface.
文摘Cavitation tests of hydraulic model were carried out in vacuum tank. A classical theory for cavitation tests in vacuum tank has been used. According to two principles, the test procedure in vacuum tank and the prediction of cavitation features on prototype were obtained. However, by using these test results it can not make a reliable prediction of cavitation feature on prototype. It shows what should be the considerable reasons for the difficulties in comparison between the results of cavitation tests in vacuum tank and how to improve the cavitation tests under a condition of vacuum pressure.
文摘This paper is mainly devoted to conduct a series of vibratory cavitation erosion tests using the magnetostriction apparatus. Distilled water was used as a standard liquid medium for comparison and other liquids were glycerine, kerosene, silicone oil and water containing different concentration glycerine and solid particles, bakerite and fly ash. Experimental results indicate that viscosity of liquid restrains, attenuates and alleviats cavitation erosion. Experiments witness that there exists critical concentration and equivalent concentration. The behaviour of cavitation clouds and the appearance of the pitting were observed. It is helpful to explain the effect of liquid quality on cavitation erosion.
