The Influence of Chromating of Electrodeposited Copper-Nickel-Chromium Coatings on Steel: Results of Five Years of Field Corrosion Testing

Abstract

The results of five years of field corrosion testing of three-layer copper-nickel-chromium coatings with an external layer of microporous chromium, unchromated and electrochemically chromated, have been described and discussed. The corrosion testing was carried out in four natural atmospheres: industrial, urban, marine, and rural. A marked positive influence of chromating on corrosion resistance and durability of tested coatings has been found. Thicker Cu20 Ni20b Cr mp, both chromated and unchromated, coatings with external layer of microporous chromium can be used in all natural atmospheres in which the testing was carried out for at least six years without any corrosion changes.

Study of high emittance chemical conversion coatings for magnesium alloys

“…(i) the samples were ground with abrasive papers (nos. 60, 240, 400, 800 and 1000) (ii) solvent degreasing in acetone using an ultrasonic bath for 3-5 min at room temperature (iii) alkaline cleaning in a solution containing 60 g L 21 sodium hydroxide, 10 g L 21 trisodium phosphate and 1?0 mL L 21 wetting agent for 5-10 min at 85-90uC followed by water rinsing (iv) acid cleaning in a solution containing 60 g L 21 chromium trioxide and 50 mL L 21 nitric acid (68%) for 10-30 s at room temperature followed by water rinsing (v) five chemical conversion coatings were then obtained using the following bath formulations and operating conditions 11,13 (vi) water rinse and air drying at room temperature.…”

“…five chemical conversion coatings were then obtained using the following bath formulations and operating conditions 11,13…”

Prototype of an expert system for selection of coatings for metals

“…Therefore, the first step was to follow the relevant and commonly used classification and coating designations to use them for development of the knowledge base framework [11][12][13][14][15][16][17][18][19][20][21][22]. 1 The domain knowledge base was worked out for solving the following design and engineering problems, e.g., as follows.…”

“…The knowledge base used for coating selection includes also their types and relevant selection criteria-featuring the Table 1 Operating conditions of coated products [13][14][15][16][17][18][19][20][21][22][23] Corrosive effect of the environment extension of the proposal put forth by Biestek and Sękowski [1] with information acquired from the pertinent standards, Table 2.…”

Investigation of Cr(III) Based Conversion Coatings on Electrogalvanised Steel

“…The Cr(VI) is present mainly in the outer layer of the coating. [7][8][9] The role of Cr(VI) in the CCC has been the subject of many studies, and valuable results have been obtained. [10][11][12][13] However, the mechanism by which CCCs protect zinc is rather complicated and is still not completely understood.…”