Adhesive coatings in the form of layers are widely used in the protection of machines and equipment against corrosion. The article presents the research of four prepared areas which were subject to the influence of brine in the Salt Spray Chamber. Powder paint was applied to one of the areas, another was covered with alkyd paint, another- with paint from spray can, and one of the areas was not protected against corrosion. The samples were exposed in a salt spray chamber. Changes oc-curring in the layers of individual coatings were registered at predetermined time intervals which were set in accordance with the standard.

In addition, coating thickness measurements were made before and after samples exposure to brine. Based on the research, it was found that the first defects of powder coated coatings appeared only after 25 hours of brine influence, in contrast to the other areas where it occurred definitely early because after only 2 hours after starting the ex-periment.The article presents the research of four prepared areas which were subject to the influence of brine in the salt spray chamber. Powder paint was applied to one of the areas, another was covered with alkyd paint, another- with paint from spray can, and one of the areas was not protected against corrosion.

1. Introduction

The varnish coating, in addition to protecting the sur-face against various external factors which are connected with the operating conditions cause that the vehicles are di-verse and also have a decorative effect on car body. An-other property of coatings consists in the vibration damping function that occurs during the operation of machines and vehicles. The varnish coating also has the task of sealing the surface on which it was applied. The most economical way to fill the gaps is to fill them with lacquer coatings. So there is no impurities and water accumulation in the gaps. Currently powder coatings are used in the protec-tion of machines and devices. It is a mixture in which all the components are in a solid form milled to a powder with a grain diameter in the range of 10-150 µm. This mixture is capable for forming on the substrate polymer coatings with the desired properties.

The basic components of powder coating systems are: crosslinking agents, resins and auxil-iary agents. During the production of varnish coatings non-observance of the technological regime causes defects. The most important of them, which are not always revealed immediately after production, include: loss of adhesion and peeling of the coating, cracking of the coating, pollination of the varnish, blistering of the coating, dulling and corrosion. The quality of coatings can be assessed through the use of developed standards. Thanks to this it is possible to determine the adhesion of the coating to the substrate, its thickness as well as its hardness. Some of the defects found in paint coatings can be detected thanks to the visual method of the using eye as well as using a magnifying glass or microscope. The purpose of the tests was to assess the quality of varnish coatings used in agricultural machines and devices made by various techniques which were subject to the in-fluence of brine in the salt spray chamber. The aluminum samples were coated with a powder coating, an alkyd paint coating and the last coating was applied as aerosol paint. Information about the results of paint coating thickness measurements at selected points both before and after the salt spray chamber test was provided.

2. Experimental study

The tests were carried out on prepared aluminum sam-ples degreased, dried and cleaned of impurities on which three different coatings were applied. One coat layer was applied to each sample surface. The powder coating, an al-kyd coating and a spray coating were applied. In addition, one of the areas was only degreased for which no corrosion protection was applied.

After each period of time, samples were rinsed and dried and then they were ob-served whether changes occurred on their surface. The samples were exposed to the brine exposure for 25 hours. After this period the thickness of coatings was re-examined and compared with previous results.

Based on preliminary measurements of the lacquer thickness a modified coefficient of variation was determined which allowed the number of 20 measurements to be taken at one measuring point.

3. Results of research

In the case of one layer of powder-coated coating at in-dividual measuring points no significant differences were found in the measured thickness of the coating. Comparing the condition of the surface of the tested sample it can be seen that the first defect on the aluminum surface covered with one layer of powder varnish appeared after 25 hours of testing. Defects on the surface are tears caused by the reac-tion of the powder coating on the sodium chloride solution.

4. Conclusions

The following statements can be made on the basis of the conducted research: (1) The best corrosion protection of machine components and devices from tested adhesive coatings is ensured by a powder coating which was characterized by the occurrence of the first defects after 25 hours of exposure to salt spray chamber. (2) For the alkyd coating and applied by aerosol paint the first defects were observed after only two hours of testing, and the most important of them are blisters and wrinkling of the coating. (3) The effect of salt spray had no significant effect on the thickness of individual coatings which were measured be-fore and after being in the salt spray chamber.

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