MXPA02001672A - Light alloy-based composite protective multifunction coating. - Google Patents

Abstract

The invention relates to a composite protective multifunction coating containing light metals and alloys thereof (A, Mg, Ti, Nb, Al-Ti, Al-Be, Ti-Nb), consisting of a hard and resistant oxide ceramic layer having the form of a matrix and of a functional composition introduced into the matrix pores. The functional compositions are selected from a group of metals (Ni, Cu, Co, Fe, Cr, Mo, Ti, Al, Sb, Ag, Zn, Cd, Pb, Sn, Bi, Zn, Ga) and/or between refractory compositions (carbides, oxides, nitrides, borides, metal silicides of groups IV - VI of the periodic table of elements). The inventive method consists in oxidizing the base by an electrolytic plasma process, introducing the functional compositions into the pores and carrying out completion by means of mechanical treatment. The inventive coating combines the properties of strength, hardness and resistance to wear and corrosion as well as predetermined plasticity and resistance to dynamic contact loads and vibrations.

Description

- * » MULTIFUNCTIONAL MULTIFUNCTIONAL PROTECTION OF M ^ TEFTlA MFXTÓ BASED ON LIGHT ALLOY FIELD OF THE INVENTION The invention can be used in different branches of engineering, electronics, medicine and other fields in which non-ferrous metals and their alloys are used. The invention relates to a technology for applying protective coatings to said metals and alloys and also to 10 components and articles made therefrom.

PREVIOUS TECHNIQUE • The use of non-ferrous alloy components with a hardening ceramic coating instead of traditional material components (ceramics, high alloy steels and cast irons) allows a considerable increase in durability and reliability of highly charged components and fast wear, a reduction in weight and an improvement in the dynamic characteristics of units. • 20 At present, a considerable amount of hard ceramic coverings has been created, but these have very significant deficiencies used in extreme conditions with insufficient lubrication or without any lubrication. Such thin coatings resistant to t? -? > Wear such as TiN, TiCN, due to inadequate wettability, often destroy the lubricating film, which leads to a greater wear rate. The relatively thick ceramic coatings are close to ceramic sintered in the nature of their frictional wear. Its main faults are a high coefficient of friction, heating of the friction interface where there is insufficient lubricant, intensive wear of the contracuerpo as a result of the effect of microcutting, corrosion and microastillamiepto of ceramic particles and their participation in the acceleration of abrasive wear . Extensive surface finishing operations for a hardness of 0.04-0.06 μm only solve this problem partially. Recently, there have been increasingly frequent attempts to create universal protective coatings for non-ferrous alloy components, capable of operating in difficult extreme conditions and still possess a low coefficient of friction, high wear resistance and good resistance to aggressive media. One way to create such coatings is the formation on the protected component of a porous ceramic coating, into which pores are introduced different fillers. Thus, there is a known method (US Pat. No. 5,487,826A) for forming a layer of mixed material in Al, Mg and Ti alloys, consisting of a porous protective oxide layer, with the introduction of fluoropolymer particles in their pores There is a known process (WO 97/05302) for forming a porous oxide film in alloys of Al, Mg and Ti, with the introduction of SiO2 particles into their pores using soi-gel technology. There is also a known process (RU 2073752) for the introduction of an organic silicon oligomer in an oxide layer formed on aluminum alloy components, with subsequent heat treatment at 300-500 ° C. A common failure for all the above procedures is the limitation of their application to high temperatures that arise when operating in extreme conditions of use of the components, and low levels for the thermal and electrical conductivity of the coatings. The factors of triboelectrisation and heat emission significantly influence the nature of wear and the formation of wear products in pairs of friction. Therefore, an increase in the thermal and electrical conductivity of mixed material coatings can be achieved by using metal or metallic type components therein. There is a known process (patent of US Pat. No. 5,645,896A) for the surface treatment of the rotor of a spiral pump that involves application to its surface, by means of the gas thermal sprinkling process, initially of a layer of rough-grained tungsten carbide at a thickness of 50-125 μm, and then a layer of chromium nickel of thickness of 75-150 μm until the carbide layer is completely coated. The final polishing reduces the rotor to its required dimensions and reveals the protective apexes on the carbon side, which to the main load when the rotor is in use. In the described procedure, the rotor is made of steel. But the thermal sprinkling procedure by gas can be used to apply coatings of virtually any composition for any reinforcement. However, it is difficult to form uniform coatings on complex shaped components by this method. In addition, the coatings applied by thermal sprinkling by gas do not bond sufficiently firmly to the base. This failure is worse if non-ferrous alloys form the base, because they quickly dissipate heat and form intensely thin oxide films under the effect of plasma jet. In addition, the non-ferrous alloys typically react at the high temperature of the dusting process, because the surfaces of aluminum and magnesium alloys can be fused, and the overheating of titanium alloys leads to a reduction in their fatigue resistance. There is a known process (patent of US Pat. No. 5,364,522A) for applying multifunctional coatings of mixed material consisting of ceramic films enriched with borides, carbides, nitrides, oxynitrides and silicides. In the first stage of the process »a hydroxide ceramic layer is applied to the reinforcement electrochemically; in the second stage, the enrichment (infiltration) of the ceramic layer with refractory compounds occurs in a gas or steam flow at a temperature of 450-800 ° C.

The coatings produced through this process are strong, resistant to wear and resistant to corrosion at elevated temperatures. However, the use of high temperatures in this technology makes it impossible to apply such coatings to components made of non-ferrous alloys. There is a known process (WO 96/13625) for the application of anti-friction and wear-resistant coatings in aluminum and aluminum alloys. The aluminum reinforcement is first anodized in a 15% solution of sulfuric acid. Then a layer of a soft metal, ie indium, tin, gallium or a combination thereof is applied to the porous anode-oxide surface. The thickness of the anode-oxide coating comprises 1-500 μm and the thickness of the metal layer ", 10-100 μm." During this procedure, at least 80% of the pores of the anode layer must be filled with metal The main problem with the described procedure is the low mechanical strength and instability of the basic anode-oxide coating.Anode coatings with a thickness of more than 10 μm have a large number of pores, which are hydrated to a considerable degree (the water content in the coating exceeds 10%), and its composition also includes 10-20% of electrolyte anions incorporated in the coating structure.When it is heated to more than 120 ° C, the electrolyte components and the water they separate from the structure of the lining, which leads to ruptures and disintegration in the anode-oxide layer and this deteriorates its protective properties.Also, the anode-oxide cs consist mainly of master phases rust traces, and as a consequence, their resistance and microhardness are not high.

BRIEF DESCRIPTION OF THE INVENTION A task of the present invention is to develop a coating of mixed material for non-ferrous alloy components, which possesses good wear resistance and a low coefficient of friction throughout the lifetime of the component, resistance to aggressive media and ability to withstand vibrations and dynamic contact charges. A second task of this invention is to develop a coating of mixed material for non-ferrous alloy components, which possesses high wear resistance and scratch resistance, resistance to wear by erosion and the action of abrasive media at elevated temperatures, and also resistance to the corrosion. A third task of this invention is to develop an ecologically safe and comparatively economical technology for the application of coatings of mixed material for non-ferrous alloys, which can be used in series production. This and some other tasks are solved by the present invention, due to the creation of a coating which has the form of a porous oxide-ceramic coating formed by the oxidation of the surface layer of the material that is protected by the method of electrolytic oxidation of plasma, in whose pores are introduced metals such as Ni, Cu, Co, Fe, Cr, Mo, Ti, Al, Sb, Ag, Zn, Cd, Pb, Sn, Bi, ln, Ga and mixtures of the same or the carbides, oxides, nitrides, borides and silicides of metals in the 5 groups IVB-VIB of the periodic system of Mendeleyev, and mixtures thereof. The formation of porous ceramic-oxide coatings on non-ferrous alloys by the plasma electrolytic oxidation method was proposed by the author of this invention in the earlier international application PCT / RU97 / 00408 (WO 99/31303). The adhesion of these coatings to the base is 5-10 times as strong as the adhesion of thermally sprinkled coatings by gas, and their strength and microhardness are 2-5 times so great, so high that they would coat the anode-oxide. 15 Oxidation occurs in aqueous alkaline and ecologically harmless electrolytes at a temperature of 15-55 ° C. Impulse voltage of 100-1000 V (amplitude value) is supplied to the components. The frequency of succession of the impulses is 50-3000 Hz. • 20 current density is 2-200 A / dm2. A thin micro oxide hardness layer of 300-2000 Hv, which depends on the composition of the alloy base, is created on the surface of the non-ferrous alloy components under the effect of Plasmochemical reactions. The thickness of the layer can be from 1 to 600 μ. By changing the electrolysis regimes and the composition of the electrolyte, significant changes can be made in the physico-mechanical characteristics of the oxide-ceramic coatings, and particularly to the magnitude of their open porosity, which can vary between 5 and 35%. As a result of studies, it has been discovered that if the above metals or carbides, oxides, nitrides, borides and metal silicides of groups IVB-VIB of the periodic system and mixtures thereof are introduced into the pores of said coating, the coating it acquires unique properties such as strength and hardness in combination with plasticity, high resistance to wear and scratching, high resistance to corrosion and resistance to vibrations and mechanical contact loads. The size of the pores varies from tens of nanometers to several microns in diameter. Pores larger than one meter comprise more than 90% of the volume of all pores. It is in these pores that the main mass of the functional compounds is introduced. The porous structure of the oxide-ceramic layer serves as a matrix for the creation of the coating of the multifunctional mixed material. Note that the porosity of the coating varies through the depth of the coating. It is at its maximum on the surface, but it is lower by a factor of 2-6 as it approaches the base metal. The concentration of functional compounds introduced into the pores is adapted to these characteristics - it is at its maximum in the layer next to the surface and decreases exponentially as the depth of the coating increases. The oxide-ceramic coatings with open porosity of 10-20% form an ideal matrix for the creation of mixed material coatings when filling this matrix with compounds that have specific properties and that fulfill specific functions (antifriction, thermal conductivity, anticorrosion, etc.) .). The microhardness of a ceramic oxide coating, on the other hand, has maximum values close to the base metal and decreases uniformly towards the outer surface of the coating (by 20-30%). The strongly developed surface of the porous structure of the matrix layer provides excellent adhesion of the functional components for the oxide coating. This gives the coating of mixed material its high resistance to cohesion. The first group of functional compounds introduced into the pores of the oxide layer consists of the soft metals Ni, Cu, Co, Fe, Cr, Mo, Ti, Al, Sb, Ag, Zn, Cd, Pb, Sn, Bi, In, Ga and mixtures thereof. The metal applies a plasticizing influence on the coating of mixed material. The specific nature of this coating is due to its deformation behavior under thermomechanical load. The two-phase ceramic-metal structure provides a fivefold increase in impact viscosity compared to pure ceramics. Said coatings can also be used as antifriction coatings. After the finishing treatment, the sectors of the ceramic oxide layer are laid uncoated. These stronger sectors on the friction surface take the main load and in this way raise the carrying capacity of the surface. In addition, the softer sectors of the surface, as they wear out, form microvoids and grooves, which serve as lubricant reservoirs, and whose presence alters the friction regime in the friction contact, facilitates the removal of the products from wear and thus improve the working capabilities of the surface. Considering the friction regime in the unit, the presence of lubricant and the state of the contact surfaces, coatings of mixed material can be formed which correspond optimally to the specific conditions of use with optimum porosity and optimum composition of the functional compounds in the pores of the material coating mixed. The second group of functional compounds introduced into the pores of the oxide layer consists of metal refractory compounds of groups IVB-VIB in the periodic system of elements of Mendeleyev: carbides, oxides, nitrides, borides and silicides. The use of these compounds separately or together with metals as functional materials introduced into the ceramic matrix of the coating, imparts to the mixed material coating such properties as high hardness and strength, resistance to high temperatures and exceptionally high wear resistance. These compounds, located in the pores, harden the coating of mixed material and alter its thermophysical and mechanical properties. All of the aforementioned functional compounds are applied to the porous ceramic matrix layer by known methods of electrolytic or chemical precipitation from aqueous or organic solutions, which include the use of ultradispersed powders, chemical or physical precipitation from gas or steam phases or the method of mechanical friction (rubbing) using powders, bars, brushes, etc. Using these methods, these functional compounds are introduced into the pores of the oxide-ceramic matrix coating at a depth of 1-150 μm, depending on the depth of the oxide coating itself and the volume of the pores therein. The work surface is finished by machine 15 (polishing, stoning, fine grinding, honing, super finishing) until the components are in the required dimensions and roughness of the surface, or until the apexes of the ceramic oxide coating are uncovered (uncoated). This machine treatment makes it possible to remove existing layers of functional compounds and distribute the part 20 remaining evenly on the surface. The machine treatment also means that there is no need to introduce xle friction surfaces. is ^ jcM ^ Mi ^ ff *? s'. ? i BRIEF DESCRIPTION OF THE DRAWINGS The attached drawings show: In Figure 1, a cross-section through a specimen with mixed material coating applied thereto, wherein 1 = functional joining material; 2 = pores in the oxide matrix coating; 3 = oxide-ceramic matrix coating; 4 = transition layer between the basic metal and the oxide coating; 5 = the basic metal. In Figure 2, a cross section of a specimen after finishing (polishing) treatment of the composite material coating. 1 = functional union material; 2 = pores in the oxide matrix coating; 3 = oxide-ceramic matrix coating; 4 = transition layer between basic metal and oxide coating; 5 = the basic metal; 6 = projections of the oxide coating on the work surface.

EXAMPLES The following examples are given as specific illustrations of the claimed invention. However, it should be considered that the invention is not limited to those specific components which are considered in the given examples.

EXAMPLE 1 (FOR COMPARISON) A specimen of alloy D16 (AICu Mg2) is in the form of a ring of dimensions D = 40 mm, d = 16 mm and h = 12 mm. The external cylindrical surface is subjected to plasma electrolytic oxidation for a period of 120 minutes in a phosphate-silicate electrolyte (pH 11) at a temperature of 30 ° C. The regime is anode-cathode; current density 20 A / dm2; magnitude (amplitude) of final voltage; anode 600 V, cathode 190 V. The depth of the oxide-ceramic coating is 120 μm, microhardness 1800 Hv, open porosity 20%.

EXAMPLE 2 A specimen of alloy D16 (AICu4Mg2) is subjected to the same treatment as in example 1, and has the following characteristics: oxide coating depth 120 μm, microhardness 1800 Hv, open porosity 20%. The specimen was subjected to chemical nickel plating and then polished.

The penetration depth of the nickel after polishing is approximately 10 μm. The nickel concentration is at its maximum in the layer next to the surface and decreases exponentially as the coating depth increases. • i An alloy specimen AK4-2 (AICu2, Mg2 Fe Ni) is subjected to plasma electrolytic oxidation for a period of 90 minutes in a phosphate-silicate electrolyte (pH 11) at a temperature of 30 ° C. The regime is anode-cathode; current density 15 A / dm2; Final voltage magnitude: 'anode 550 V, cathode 120 V. The depth of oxide-ceramic coating 70 μm, microhardness 1550 Hv, open porosity 16%. A layer of mixed material consisting of 20% Cr and 80% Cr3C2 is applied to the specimen by the chemical precipitation method from the gas phase. During the precipitation, the specimen was heated to 300 ° C. After this, the specimen was polished. The penetration depth of the functional compound Cr-Cr3C2 in the porous structure was approximately 7 μm.

EXAMPLE 4 An alloy specimen VT6 (TiAlβV4) was oxidized in an aluminate-sulfate electrolyte (pH 9) for 20 minutes at a temperature of 20 ° C. Regime: anode; current density 50 A / dm2; final anode voltage magnitude 300 V. Depth of oxide coating 15 μm \ microhardness 690 Hv, open porosity 12%.

A layer of nickel was applied to the specimen through the chemical precipitation method before the gas phase. During the precipitation, the specimen was heated to 200 ° C. After this, the cylindrical surface of the specimen was polished. The penetration depth of the nickel compound in the porous structure was 3 μm.

EXAMPLE 5 An alloy specimen VMD12 (MgZn6MnCu) was oxidized in an aluminate-fluoride electrolyte (pH 12) for 40 minutes at a temperature of 20 ° C. Regime: anode-cathode; current density 8 A / dm2; final voltage magnitude: anode 350 V, cathode 130 V. Depth of the oxide-ceramic coating 30 μm, microhardness 750 Hv, open porosity 25%. A layer of mixed nickel material was applied to the specimen through the chemical precipitation method from the gas phase. During precipitation, the specimen was heated to 200 ° C. After this, the cylindrical surface of the specimen was polished. The penetration depth of the nickel compound in the porous structure of the layer was 10 μm.

EXAMPLE 6 An ABM-3 alloy specimen (AIBe6oMg2) - of the "local alloy" type was oxidized in a phosphate-silicate electrolyte (pH 11) for 120 minutes at a temperature of 30 ° C. Anode-cathode regime; current density 15 A / dm2; final voltage magnitude: anode 480 V, anode 110 V.

Depth of coating of oxide-ceramic 100 μm, microhardness 790 Hv, open porosity 18%. A layer of mixed nickel material was applied to the specimen through the chemical precipitation method from the gas phase.

During precipitation, the specimen was heated to 200 ° C. After this, the cylindrical surface of the specimen was polished. Penetration depth of the nickel compound in the porous structure of the oxide layer: 8 μm. In a universal friction machine tests were performed friction pairs formed of components with different types of coating and against specimens of hardened steel. A ring-cylinder arrangement with intersecting axes for point contact was selected. A fixed specimen of steel ShKh15, hardness HRC3 58-60 was pressed into the movable specimen (rings) to which the coating under study had been applied. The tests were carried out in the limit friction regime, in which several drops of spindle oil were applied to the coated specimen before the test. The sliding speed was 2 m / sec, normal load at the contact of the specimens -75N. The test took 60 seconds. Ten identical tests were performed on each ring. The mean values for the characteristics were calculated from the results of these tests.

The studies also served to evaluate such friction characteristics as wear resistance, friction coefficient and load capacity. The wear resistance was assessed from wear in weight and dimensions by comparing the dimensions of points in the steel specimen and the loss of mass of the coated specimen. The results of the technical friction tests are given in table 1.

TABLE 1 The test results demonstrate the efficiency of using mixed material coatings in different reinforcements compared to the usual aluminum oxide ceramic coating. In this way, the coefficient of friction is slightly more than half, the wear of counter-bodies is reduced by a factor of 2-5 and wear of the ring coating itself by a factor of up to 10.

Industrial application Because the proposed composite material coating has such unique properties as high strength and hardness in combination with a certain plasticity, exceptional resistance to wear and scratching, and high resistance to corrosion and vibration, there is the opportunity to considerably expand the application of non-ferrous metals components. It also increases the durability and reliability of components that operate in extreme conditions under the simultaneous effect of different forms of wear (abrasive wear at high temperatures and in aggressive media, vibration and dynamic contact loads). The wide scale of metals and refractory composites used as functional materials introduced into the porous ceramic matrix makes it possible to select the optimum characteristics of mixed material coating for real conditions of use. The proposed method for producing protective coatings is distinguished by being ecologically harmless and by its low costs, and is suitable for use on an industrial scale.

Claims (14)

NOVELTY IS THE INVENTION CLAIMS

1. - A coating of protective mixed material, applied in non-ferrous metals, its alloys and intermetallic compounds, and also in compounds derived therefrom, characterized in that the coating of mixed material takes the form of a first porous oxide-ceramic matrix coating. , formed by plasma electrolytic oxidation of a surface layer d of a material to be protected, and a second coating formed by introducing at least one functional component selected from the group comprising: Ni, Cu, Co, Fe, Cr, Mo, Ti, Al, Sb, Ag, Zn, Cd, Pb, Sn, Bi, In, Ga and mixtures thereof, ßarburos, oxides, nitride, borides and silicides of the metals of groups IVB-VIB of the periodic system of elements of Mendeleyev, and mixtures thereof; in the pores of the first matrix coating; characterized in that surface portions of the first matrix coating protrude beyond the second coating.

2. The coating of mixed material according to claim 1, further characterized in that it is applied to the non-ferrous metals Al, Mg, Ti, Nb and their alloys, and also the compounds Al-Ti, Ti-Nb and Al- Be. t * + 4 * *

3. - The composite material coating according to claim 1 or 2, further characterized in that the ceramic oxide-ceramic coating has an open porosity of 5-35%, with the porosity decreasing through the thickness of the coating in the direction toward inside from the outer layer, the microhardness of the ceramic oxide coating is 300-2000 HV and increases through the thickness inwardly from the outer layer, and the total thickness of the oxide-ceramic layer comprises 1-600 μm, preferably 3-150 μm.

4. The coating of mixed material according to claim 3, further characterized in that the oxide-ceramic matrix coating has an open porosity of 10-12%.

5. The coating of mixed material according to any of claims 1, 2, 3 or 4, further characterized in that the functional components are introduced into the pores of the oxide-ether matrix coating at a depth of 1-150 μm , preferably 2-100 μm.

6. A process for applying a coating of mixed protective material to non-ferrous metals, their alloys and intermetallic compounds, and also to components made from them, characterized in that it includes the following steps: (a) electrolytic oxidation of plasma of a surface layer of the material that is protected, with a controlled process voltage and current density in order to produce a first ceramic-oxide matrix coating with porosity default; (b) introduction into the pores of the first ceramic-oxide matrix coating formed in step (a) of at least one functional component selected from the group comprising: Ni, Cu, Co, Fe, Cr, Mo, Ti, A4, Sb, Ag, Zn, Cd, Pb, Sn, Bi, In, Ga and mixtures thereof, 5 carbides, oxides, nitrides, borides and silicides of the metals of groups 1VB-VIB of the periodic system of elements of Mendeleyev, and mixtures thereof; so as to form a second coating; and (c) finishing the surface of the composite material coating so as to cause surface portions of the first matrix coating to protrude further from the second coating.

7. The method according to claim 6, further characterized in that the electrolytic oxidation of plasmas occurs at a voltage of 100-1000 V and at a current density of 2-200 A / dm2.

8. The process according to claim 6 or 7, 5 further characterized because the electrolytic oxidation of plasma occurs at a temperature of 10-55 ° C. 9.- The procedure in accordance with any of the! claims 6, 7 or 8, further characterized in that the introduction of the functional components into the pores of the first matrix coating is * ß 20 performs through electrochemical precipitation from aqueous or organic solutions, which include the use of ultradispersed powders. 10. The method according to any of claims 6, 7 or 8, further characterized in that the introduction of the *** - functional components in the pores of the first matrix coating is carried out by chemical precipitation from aqueous or organic solutions. 11. The process according to any of claims 6, 7 or 8, further characterized in that the introduction of the functional components into the pores of the first matrix coating is carried out by chemical precipitation from the gas phase. 12. The process according to any of claims 6, 7 or 8, further characterized in that the introduction of the functional components into the pores of the first matrix coating is carried out with the aid of physical precipitation methods. 13. The process according to any of claims 6, 7 or 8, further characterized in that the introduction of the functional components into the pores of the first matrix coating is 15 performed with the help of mechanical rubbing by friction, using powders, bars or brushes. 14. The method according to any of claims 6 to 13, further characterized in that the finishing treatment of the mixed material coating is selected from the following operations: polishing, fine grinding, stoning, grinding and super finishing.