SU1465748A1 - Method of determining adhesion of coating with base material - Google Patents

Abstract

The invention relates to a test technique, is intended to determine the strength of adhesion of a coating to a substrate, and reduces the duration and accuracy of determination by taking into account the effect of the resistance of the transition zone of the coating materials and substrate. Compound of metallic base and 1 The invention relates to a test technique, and specifically to methods for determining the strength of the bond and coatings with bases. The purpose of the invention is to reduce the duration and increase the accuracy in determining the strength of adhesion of the pokralti to the substrate by taking into account the influence of the resistance of the transition zone of the coating materials and the substrate. The process is as follows. The coatings are placed in an electrolyte, supplied to the base. A constant electric current, whose density is maintained, is kept in the range of 3.0–30.0 A / cm, and the voltage is increased to 250–800 V. This energy causes intense diffusion and saturation of the coating and the transition zone with hydrogen, which contributes to the rapid destruction of the coating in the areas with defects. The moment of destruction of the coating is recorded by the occurrence of a corona discharge on its surface. Increasing the current density above 30.0 A / cm and a voltage above 800 V leads to a strong melting of the metal base and hides places with a defective coating; a decrease in the current density below 3.0 A / cm and a voltage less than 250 V increases the duration testing process. The diffusion does not penetrate the transition zone of the joint. A test coating is deposited on a metal base with one of the known methods. The compound obtained is placed in an electrolyte solution. A constant electric current is passed through the base, the density of which is maintained within 3.0-. 30.0 A / cm, and increase its voltage to 250-800 V, Electrochemical / oxidation processes (with anodic polarization) or reduction (with ka (L O) SP. 4 00

Description

3.1465

suitable polarization) of water, the resultant (JM of which is the formation on the surface of the coating of a passive layer (a gas envelope of hydrogen or oxygen) and the passivation of the surface of the test sample.

At a voltage of 250 V and above, a corona discharge occurs on the surface of the coating, which leads to ionization of the gas envelope, i.e. causes the formation of low-temperature plasma. Due to the high temperature (all electrical energy supplied is dissipated as heat), the diffusion and saturation of the coating and the transition layer by hydrogen is intense. This leads to rapid destruction (spalling) of the coating in areas with defects (voids, cracks, chips, etc.),

Corona zone depends on the quality of the coating. If there are defects in the coating (cracks, chips, inclusions, high resistance in the coating zone - base metal or coating electrolyte solution, etc.), corona discharge occurs in the transition zone (coating - base metal or coating. - electrolyte solution). It also leads to the destruction of coating areas that have obvious or hidden defects. The corona discharge and plasma-chemical processes are accompanied by high temperature (more than 30,000 C), intense light radiation, cavitation processes, abundant gases, healing — these factors reduce processing time and increase the accuracy of the test. The emergence of a steady corona discharge and the need for visual inspection of the test coating.

In the presence of patches, destruction of the coating is observed; in case of high-quality coating, no degradation occurs or the coating melts. At current density and voltage

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The scientific research institutes less, respectively, 3.0 A / cm and 250 V noticeably increases the testing time and decreases the accuracy; An increase in the current density and voltage of more than 30 A / cm and 850 V leads to a strong melting of the base metal, which makes it difficult to control the test results,

The adhesion strength of the coating to the substrate is determined by the presence of bubbles in the coating after the compound has been removed from the electrolyte. The smaller the blister coating on the surface, the higher the adhesion strength of the coating to the substrate.

PRI me R. An oxide ruthenium-titanium coating is applied to the substrate. The compound is placed in an electrolyte based on a salt solution of the deposited metal. The current density is 15 A / cm. The voltage is increased to 300 V. The moment of the corona discharge occurs after 15 s. A flaking of the coating is observed at 45% of its surface;

Claims (1)

Invention Formula A method for determining the adhesion strength of a coating to a substrate. By applying a test coating to a metal substrate, placing the compound in the electrolyte solution, passing an electric current through the substrate, increasing its voltage, maintaining the compound in the electrolyte until the coating is destroyed, and determining the adhesive strength of the coating Based on the presence of bubbles in the coating, characterized in that, in order to reduce the duration and increase the accuracy of determination, the density of the electric current is maintained within 3.0-30.0 / Cm, increasing voltage is performed to 250-800 V, and the time degradation of the coating was monitored by the appearance of the coating on the surface of a corona discharge electric current. 45 50