RU2581329C1 - Catalytically active thermal barrier ceramic coating on surface of chamber of internal combustion engine - Google Patents

Abstract

FIELD: engines.

SUBSTANCE: invention relates to a wear-resistant catalytically active thermal barrier ceramic coating of parts of internal combustion engine chambers, deposited by micro-arc oxidation. Said coating is double-layer with thickness of 15-150 mcm. First coating layer has thickness 5-100 mcm with aluminium content of not less than 90 mol%. Second porous layer with thickness of 10-100 mcm consists of aluminium oxide and cerium oxide with content of 1 to 50 mol%.

EFFECT: higher reliability and efficiency of chamber of internal combustion engine, higher efficiency of internal combustion engine, reduced emissions of carbon monoxide, carbon dioxide and hydrocarbons into environment.

1 cl

Description

The invention relates to wear-resistant catalytically active ceramic coatings that can be used in internal combustion engines (ICE).

A known method of preparing a catalyst for cleaning exhaust gases with increased activity and mechanical strength (SU No. 733717, B01J37 / 00, publ. 05/15/1980). In this method, before applying the catalytically active layer, the titanium plate is anodized in solutions of hydrochloric and sulfuric acids.

The disadvantage is that this method allows to obtain an oxide porous layer only on titanium.

A known method of obtaining a protective coating (RU No. 2089655, C23C 14/06, publ. 09/10/1997), comprising the sequential deposition of two metal and ceramic layers, the metal layers are applied in vacuum and after applying the metal layer conduct diffusion vacuum annealing, the ceramic layer is deposited with a thickness of 70-300 μm, after which the ceramic coating layer is hardened by high-temperature pulsed plasma, followed by oxidative annealing at a temperature of at least 1050 ° C for at least 5 hours.

However, such a coating is unreliable and short-lived during operation, since upon receipt of the coating by this method in the ceramic layer there are defects in the form of channels and cavities through which oxygen of the working (gaseous medium) accesses the metal and, as a result, oxidation of the metal coating under the ceramic , which leads to the delamination of the ceramics and its premature cracking.

A known method of obtaining a protective coating on the parts (RU No. 2305034, C23C 14/28, publ. 08.27.2007). At least one metal layer is applied to the surface of the part. Then carry out alitization or chromoalithium. After that, a ceramic layer based on zirconium oxide containing yttrium oxide is applied. The hardening of the ceramic layer is carried out by applying at least three ceramic layers based on zirconium oxide containing 6-9% yttrium oxide and 3-30% aluminum oxide. This method improves the reliability and durability of the protective coating.

Unlike the claimed catalytically active coating applied to the internal combustion engine piston, cerium oxide is not added to the analogue composition, which is an effective catalyst accelerating the process and completeness of fuel combustion, which is necessary when the engine is running. Also in a similar invention, the coating layers are applied by methods such as vacuum-plasma, diffusion, electron-beam, cathode and laser sputtering, in our invention, the coating is formed by the method of microarc (plasma electrolytic) oxidation, this method is characterized by higher adhesion resistance, resistance to thermal shock and thermal cycling.

The closest analogue is a method for producing oxide catalytically active layers and catalytically active material obtained by this method (RU No. 2152255 C1, IPC BJ 37/34, July 10, 2000). The method of producing oxide catalytically active layers on a substrate made of valve metal or its alloy, mainly aluminum, by oxidizing the substrate in an electrolyte. The process of microarc oxidation in an alkaline electrolyte with the addition of ultrafine powders of metal oxides and transition metal salts is used as the oxidation treatment. The material obtained by this method has a high developed surface due to the resulting structure of the oxide layers, as well as significant heat resistance and wear resistance.

The challenge facing the authors is to increase the reliability and efficiency of the internal combustion engine of the engine, increase the efficiency (ICE) of the internal combustion engine, reduce emissions of carbon monoxide (CO), carbon dioxide (CO ₂ ) and hydrocarbons into the environment.

The problem is solved thanks to the catalytically active ceramic thermal barrier coating formed by the method of microarc (plasma electrolytic) oxidation on the piston and cylinder head of the combustion chamber of the internal combustion engine.

The essence of the invention consists in the formation of a catalytically active ceramic thermal barrier two-layer coating, consisting mainly of aluminum oxide and cerium oxide, by the method of microarc (plasma electrolytic) oxidation on the piston and the cylinder head sphere of the ICE combustion chamber.

The oxide layers obtained by the microarc oxidation method are characterized by high adhesion, resistance to thermal shock, and thermal cycling.

Cerium oxide, as well as its binary and ternary oxides (including with aluminum) are effective catalysts for the conversion of hydrocarbons and carbon monoxide (CO) at sufficiently low temperatures (about 500 ° C, which corresponds to the conditions of the chamber of an internal combustion engine), accelerating the process and completeness of fuel combustion.

The technical solution of the invention.

A two-layer catalytically active thermal barrier ceramic coating with a thickness of 15-150 microns is formed on the piston and the sphere of the cylinder head of the combustion engine of the internal combustion engine by the method of microarc (plasma electrolytic) oxidation. The first (inner) coating layer, 5-100 microns thick, consists mainly of aluminum (at least 90 mol.%) And is in direct contact with the metal of which the piston and the head of the ICE chamber sphere are made. The first layer has high hardness and wear resistance. The second (outer) porous layer, 10-100 microns thick, consists of aluminum oxide, silicon oxide and cerium oxide in a mole fraction of 1 to 50%. The second layer has high adhesive strength, resistance to thermal shock and thermal cycling, and also has a thermal barrier and catalytic effect. Additionally, the coating may contain oxides of copper and magnesium.

The technical effect of the use of a catalytically active ceramic thermal barrier coating in the operation of the chamber of an internal combustion engine is:

- increase in temperature in the combustion chamber;

- increase the completeness of fuel combustion;

- reduction of emissions of carbon monoxide (CO), carbon dioxide (CO ₂ ) and hydrocarbons in the environment;

- reduction of thermal load on the cooling system and other engine parts;

- as a result, an increase in the efficiency of ICE.

Thus, the task facing the authors is to increase the reliability and efficiency of the engine’s internal combustion engine chamber, increase the internal combustion engine’s efficiency (COP), and reduce the level of carbon monoxide (CO), carbon dioxide (CO ₂ ) and hydrocarbon emissions into the environment completed.

Claims (1)

Wear-resistant catalytically active thermal barrier ceramic coating of parts of the chamber of an internal combustion engine, applied by microarc oxidation, characterized in that the coating is a two-layer thickness of 15-150 μm, while the first coating layer is made of 5-100 μm thickness with an aluminum content of at least 90 mol. %, and the second porous layer with a thickness of 10-100 μm consists of aluminum oxide and cerium oxide with a content of from 1 to 50 mol.%.