opk Current issue
Galvanized coatings in connecting difficult-to-bond materials.
Pt. 2. Influence of surface preparation on the adhesion of galvanized coatings deposited on passivating metal substrates
Technologie Galwaniczne Sp. z o.o
Problems concerning the preparation of 7075 aluminium alloy and non-alloy Grade 2 titanium for electrochemical application of galvanic coatings have been presented. A copper layer, a copper-chromium alloy coating and a nickel-phosphorus alloy coating were deposited onto the surface of materials prepared using various methods. Afterwards, tests were carried out to determine the thickness and composition of the applied coating, its wettability and adhesion to the substrate..
Keywords: 7075 aluminium alloy, non-alloy Grade 2 titanium, surface activation, galvanic coatings, thickness, chemical composition, adhesion
Vol. 62, nr 11, pp. 364-371
The structure and corrosion resistance of the cross-section of the boronized AISI 321 stainless steel
Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology
The effect of the boronized AISI 321 steel on its structure, mechanical properties and corrosion resistance in a deaerated sulphate solution is presented. The AISI 321 steel was boronized with the use of the gas-contact method for 6 hours at a temperature of 900°C. After completion of the boronizing process, the steel surface was examined by optical microscopy and with a scanning electron microscope. The thickness of the boronized coating was evaluated based on the microhardness of the cross-sectional surface layer. Potentiokinetic polarization tests were carried out in an acidified (pH = 4) 0.5M sulphate solution. It has been shown that the boronizing of the AISI 321 steel results in a substantial improvement in the hardness of the surface layer of the material treated and impairs the corrosion resistance. The rate of the corrosion of the thermochemically treated outer layers of the examined steel is 3-4 times higher than the corrosion rate of the matrix. The passive-state characteristics are particularly impaired, which manifests itself in an increase in the values of the critical passivation current and the minimum passive-range current, and in a reduction in the tendency to secondary passivation.
Keywords: corrosion, stainless steel AISI 321,boride layer
Vol. 62, nr 11, pp.372-375
CORROSION PROTECTION IN PRACTICE
Research on the effectiveness of corrosion inhibitors used periodically in the mining industry
Instytut Nafty i Gazu – Państwowy Instytut Badawczy, Kraków
In recent years, after the economic crisis, scientists have conducted a lot of research to reduce production costs. In the industry, instead of corrosion inhibitors for continuous use, corrosion inhibitors used periodically have been introduced. The aim of the research described in the article, was to assess the effectiveness of the inhibitor used periodically. The test results showed that after the use of corrosion inhibitor applied periodically in gas wells, the corrosion rate decreased to values from 0.0129 mm / year to 0.0046 mm / year and in oil wells from 0.0142 mm / year to 0.0023 mm / year.
Keywords: corrosion inhibitors for continuous use, corrosion inhibitors used periodically
2019, Vol. 62, nr 11, pp. 376-381