The method of blasting products

 

(57) Abstract:

The invention can be used for surface preparation of steel products to the plasma spraying, cleaning descaling, peening of metal products and corrosion protection. The invention aims to improve the adhesion of thermal spray coatings to the substrate. This is achieved in that on the surface of the product serves the steel fraction containing 45-50 wt.% the fraction of chrome steel. 3 table.

The invention relates to the processing of products fraction and can be used primarily for surface preparation of steel parts to the plasma filling, cleaning descaling, peening of metal products and corrosion protection.

There is a method of blasting in which the surface of the product serves a mixture of steel and aluminum fractions of different diameters, and aluminum fraction is 25 to 30% of the total weight of the mixture, and the diameter of an aluminum fraction in 2 to 3 times smaller than the diameter of the steel.

The disadvantage of this method is that it contributes to reducing the adhesion strength of thermal spray coatings. When preparing the surface is the second layer of aluminum, covered with oxides. Oxides of aluminum have a high activation energy and perform the activation barrier for the flow of processes of chemical interaction between the sprayed particles to the substrate, the formation of diffusion and, as a consequence, a strong adhesive bond between them.

The invention aims to improve the adhesion of thermal spray coatings to the substrate (adhesion).

This is achieved by the fact that the fraction serves on the surface of the product in the form of a mixture with 45 to 50% weight content of the fraction chromium steel.

Comparative analysis of the prototype allows us to conclude that the claimed method differs from the known fact that during its implementation fraction serves on the surface of the product in the form of a mixture with 45 to 50% by weight content of chromium steel. It provides education on the surface of the workpiece layer of chromium, having a high diffusion mobility and contributing to increase the adhesion of the coatings.

The claimed method blasting products corresponds to the category of "novelty" and allows to make a conclusion about its compliance with the criterion of "significant difference".

A forceful impact leasuithe surface topography, the saturation of its structural defects. This helps to increase the energy of the surface atoms and the speed of their diffusion in the process of chemical interaction with the molten particle.

The fraction chromium steel on impact with the surface is deformed. When this material fraction is transferred to the surface of which is covered with a layer of chromium of a thickness (~300). Chrome on the surface of workpiece is held due to forces of mechanical gearing and the non-bonded interaction forces (type forces van der Waals forces).

At thermal spraying the adhesive strength of the coating to the substrate depends on the depth of the mutual diffusion penetration of the atoms of the fused particles and sputtered surface. Chrome, whose diffusion coefficient in metals than aluminum (PL.1, 2), in contact with the molten particle will prodifferent in the coating and the substrate on the big clay, providing a more durable adhesive bond.

Decreasing the weight content of the fraction chromium steel in a mixture below 45% the intensity and quality of the processed surface is reduced, which reduces the adhesion strength of thermal spray coatings. The expansion of the coating and is not economically advisable.

Example. Studies were conducted on steel samples cut from radical necks of a cranked shaft of the engine ZIL-130. Shot blasting of the samples was carried out on pneumogastric installation ejection deployme nozzles at a pressure of compressed air 0.4 to 0.6 MPa.

As an abrasive was used a mixture of steel shot DSC (GOST 11964 - 81) and the fraction made of a thin sheet of chrome steel H (GOST 5582-75) in a ratio of approximately 1 to 1.

Quality assessment of sample processing was performed according to the value of the adhesion strength of coatings (powder PNU) with the disengagement of the normal. Moreover, the thickness of the deposited layer was 0.8 mm, the time between processing and plating 1 minutes Technological options for processing samples and their corresponding values of adhesion of the coatings are presented in table 3.

The analysis of the table shows that the best values of the adhesion strength obtained for variants 6, 7, 8, but a lower percentage fraction of chrome steel with maximum adhesion corresponds to the sixth embodiment. This allows us to consider this option is the most rational for the implementation of the intended method of shot peening.

The method of blasting products, including applying to the surface a mixture of steel shot, characterized in that on the surface of the product serves a mixture containing 45 to 50 wt. fraction chromium steel.

 

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