UA149762U - METHOD OF STRENGTHENING WORKING SURFACES OF PISTON RINGS OF INTERNAL COMBUSTION ENGINES - Google Patents

Abstract

Method of strengthening working surfaces of reciprocating rings of internal combustion engines of cast iron and steel, including air-plasma deposition of a layer of Ni-C-Cr-Si-B-Fe (nickel - base) at I = 280-320 A, U = 40-50 V, spray distance 100-120 mm and constant parameters: speed of rotation of samples - 45 rpm, linear speed of movement of samples relative to the plasma jet - 18.4 m / min; the diameter of the charge line in the nozzle of the anode - 2 mm; the distance from the point of introduction of the powder to the cut of the nozzle - 4 mm; the axis of the plasma jet is perpendicular to the axis of rotation of the sample, followed by gas-thermal melting of the surface, before plasma spraying is carried out abrasive blasting of silicon carbide with a particle size of 1.1-1.3 mm, and spraying is carried out , in the following ratio of components, weights. %: carbon 0.6-1.4, chromium 12-20, silicon 2.4-4.8, boron 2.0-4.3, iron 3-7, Nickel - the base, resulting in the surface of the parts form wear-resistant coating with a thickness of 180 to 200 microns, depending on the size of the part and the conditions of its operation.

Description

The useful model belongs to the field of mechanical engineering, namely to methods of strengthening the working surfaces of piston rings of internal combustion engines by air-plasma spraying with the use of subsequent gas-thermal heating of the surface and can be applied to strengthen the working surfaces of auto tractor engine parts.

Piston rings are elements of seals on pistons, for example, an internal combustion engine or a piston compressor. In an internal combustion engine, piston rings seal the gap between the piston head and the cylinder wall, separating it from the combustion cavity. In modern engines, a total of three piston rings are used per cylinder, the performance of which depends on their location. The main task of the piston ring closest to the combustion cavity, the so-called compression ring, is to seal and remove heat. It is the lower ring, the so-called oil-receiving ring, that removes the lubricant from the cylinder wall and at the same time dispenses the oil film through which the upper rings slide during lifting. The middle ring plays an important role in regulating oil consumption and additionally seals against combustion gases.

During the reciprocating movement of the piston, on the one hand, the piston ring slides on its outer circumferential surface relative to the cylinder wall with constant spring pressure against it, on the other hand, due to the change in the direction of the piston movement, the piston ring alternately slides in its groove for the piston ring, and its end sides alternately adjoin the upper or lower side of the groove. With the corresponding relative movement, the parts rub when sliding and, depending on the material from which they are made, more or less wear occurs, which in case of dry friction can lead to the so-called burr of the piston, the formation of grooves and ultimately to the destruction of the engine.

In order to manufacture intensively loaded parts of internal combustion engines, such as piston rings, cast iron or cast iron alloys are mainly used.

The chemical composition of cast iron for the manufacture of piston rings is given in Table 1.

In intensively loaded internal combustion engines, such as 4-stroke and 2-stroke engines, piston rings, especially compression piston rings, are subjected to increasingly high loads. Among other things, piston rings are affected by high peak compression pressure, high combustion temperature and reduction of the lubricating film, which significantly affect

From functional properties, such as wear resistance, resistance to the formation of burning, microwelding and corrosion resistance.

There are well-known methods of applying condensation and diffusion coatings, each of which has its own varieties (Kolomitsev P.T. High-temperature protective coatings for nickel alloys.

M.: Metallurgy, 1991. - 236 p.|.

Thermal protective coatings are characterized by lower thermal conductivity, but crack and peel off during thermal changes under the influence of thermomechanical loads.

Electrolytic chrome coatings and heat-protective coatings obtained by the method of electron beam sputtering or plasma deposition in air or in a vacuum are effectively used to ensure the performance of parts of the cylinder-piston group

Increasing the wear resistance of internal combustion engine parts. M.M. Khrushchev - M.:

Mechanical engineering, 1972.|.

Electrolytic chrome coatings mainly meet the specified requirements of existing industries. The hardness of the specified coatings is at the level of 900-1000 NU, adhesive strength - up to 700 kg/sme, relatively low coefficient of friction, satisfactory wear and oil absorption, high thermal conductivity.

However, due to the impossibility of applying electrolytic chromium deposits of more than 200 microns, their service life is sometimes lower than the service life of engines before the 1st repair. And increasing the hardness of the coating reduces the fatigue life of the ring in the sleeve and requires high precision in the manufacture of rings. Due to the insufficient thickness of the coating, further processing for the geometry of the sleeve is quite difficult and time-consuming.

Electrolytic chromium works unsatisfactorily for friction and wear at high temperatures due to a sharp decrease in hardness (at 300 "С the hardness is 800 kg/mm-, and at 700 706-200 kg/mm7). Due to the fact that there is no polymorphic transformation in chromium precipitates, then heat treatment does not increase the hardness of coatings. If the coating has insufficient porosity, then at a temperature of more than 300 "C, hard chrome is unworkable in conditions of unsatisfactory lubrication - burning and burrs occur. A local increase in temperature leads to intense softening, seizure, and chipping of coatings. In the process of working, the porous layer significantly loses its strength due to fatigue wear in conditions of elevated temperatures. Due to the fact that the temperature coefficient of linear expansion of chrome coatings is lower than that of the ring material (cast iron, steel), tensile stresses may occur in the coating, contributing to thermocyclic and corrosion cracking of the coatings. In diesel engines, as a result of the presence of sulfur in the fuel, the formation of sulfuric acid is possible, which can lead to the formation of galvanic vapor in contact with the cylinder and sulphide corrosion.

There is a known method of applying a chrome coating to steel parts (Invention Patent of the Russian Federation 2269608, C23C 4/04, published on February 10, 2006, Bull. Mo 4|Y. In this method, the wear resistance of the coating is not increased, but the adhesion of the coating and productivity are increased.

There is a known method of applying a combined heat-resistant coating on turbine blades, which includes chromoalization in a powder mixture followed by thermal vacuum treatment, after which an electron beam sputtering of a layer of ceramics 2г02-8У203 is carried out on the inlet edges of the blades with subsequent annealing for the final formation of the coating (Patent for the invention

RF Mo 2272089, cl. С23С 28/00, publ. 20.03.2006, Bull. Mo 8), the composition of which corresponds to the operating conditions of the outer surface of the working blades of the gas turbine engine and is unacceptable for parts of the cylinder-piston group of auto-tractor machinery.

The closest technical solution, chosen as the closest analogue, is the method of applying a heat-resistant wear-resistant coating on cast iron and steel parts, which includes plasma spraying of the sublayer of the composition of Co-St-AI-X and subsequent spraying of a cermet composition from a mechanical powder mixture of 20-50 weight . 96 nichrome, 50-20 wt. 96 of zirconium dioxide with a stabilizing additive, 20 wt. 95 of chromium carbide, 10 wt. 95 tungsten carbide. At the same time, yttrium oxide is used as a stabilizing additive in zirconium dioxide powder, the content of which is 4-7 wt. 95 (Invention patent of the Russian Federation No. 2425906, class C23C 4/04 (2006.01), C23C 24/04 (2006.01) published on August 10, 2011, Bull. Mo 22). The invention provides an increase in the resistance of the coating to abrasion, hardness of the coating, heat resistance, adhesion of the coating to the base metal.

The disadvantage of similar methods and materials used, including the closest analogue, is the use of expensive and scarce materials for Ukraine, in particular nichrome and yttrium, which complicates their use. This does not allow using the mentioned methods and materials in industrial volumes.

The main reasons why it is impossible to obtain the technical result that is achieved in analogs and the closest analog are insufficient hardness, unsatisfactory wearability, scarcity of the materials used.

To increase the resistance of the coating to abrasion during friction, it is necessary to increase the hardness, wear resistance, and plasticity of the coating, to ensure the uniformity of the thickness of the coating while simultaneously increasing it.

The technical task of the useful model is to improve the tribological properties of piston rings as a result of thermal spraying followed by remelting of the surface of a previously unused system of coating materials, compared to coatings of piston rings made using the galvanic method or thermal spraying.

The essence of a useful model is that in the method of applying a heat-resistant wear-resistant coating to cast iron and steel parts, which includes preliminary abrasive blasting of surfaces for a certain time with silicon carbide with a particle size of 1.3-1.6 mm, followed by powder spraying mixture, and during the application of a heat-resistant wear-resistant coating on cast iron and steel parts, which includes air-plasma spraying of a layer of the composition Mi-b-St-5i-V-Ee (nickel - base) at I - 280-320 A, 0О- 40-50 V, spraying distance 100-120 mm and constant parameters: speed of rotation of samples - 45 rpm, linear speed of movement of samples relative to the plasma jet - 18.4 m/min; the diameter of the water charge in the anode nozzle is 2 mm; the distance from the place of introduction of the powder to the section of the nozzle - 4 mm; the axis of the plasma jet is perpendicular to the axis of rotation of the sample, with subsequent gas-thermal melting of the surface, before plasma spraying, abrasive jet treatment with silicon carbide with a particle size of 1.1-1.3 mm is carried out, and spraying is carried out from a self-flowing mechanical powder mixture, which additionally contains chromium carbide , with the following ratio of components, weights. In: carbon 0.6-1.4, chromium 12-20, silicon 2.4-4.8, boron 2.0-4.3, iron 3-7, nickel - the base, as a result of which on the surface of the parts they form wear-resistant coating with a thickness of 180 to 200 microns, depending on the size of the part and its operating conditions.

According to the information available to the applicant, the set of essential features characterizing the essence of the applied utility model is not known from the state of the art, which allows us to conclude that the utility model meets the "novelty" criterion.

The claimed useful model can be repeatedly implemented in mechanical engineering using known means, and with obtaining the expected technical result, which allows us to draw a conclusion about its compliance with the "industrial suitability" criterion. Thus, the composition of the coating and the method of obtaining the coating on the piston rings, which is claimed, is a technical solution that meets all the conditions of patentability of the utility model.

The proposed method of applying a wear-resistant coating is implemented in the following way.

The coating is applied to the compression and oil-receiving piston rings of auto-tractor machinery.

The material of the piston rings is low grade (gray) or high grade (high strength) cast iron with a hardness of 96-112

HB for gray or 100-112 HB for high-strength cast iron.

For sputtering, an air-plasma sputtering unit of the UMIP-6 type is used as a part of the power source ISN-160/600-Ш, plasmatron PP-25, powder feeder.

Sputtering is carried out on an installation equipped with a rotator and a device for moving the plasmatron. Before spraying the coatings, abrasive jet treatment with silicon carbide with a particle size of 1.3-1.6 mm is carried out. Self-fluxing mechanical powder mixtures are used, which additionally contain chromium carbide, with the following ratio of components, weight. In: carbon 0.6-1.4, chromium 12-20, silicon 2.4-4.8, boron 2.0-4.3, iron 3-7, nickel - base. Sputtering of coatings according to the proposed method is carried out with an air plasmatron PIP-25: at 1-280-320 A, 0-40-50 V, sputtering distance of 100-120 mm with subsequent gas flame melting of self-fluxing alloys. The thickness of the coatings is 180-200 microns.

Plasma sputtering is carried out with the following constant parameters: rotation speed of samples 45 rpm, linear speed of movement of samples relative to the plasma jet - 18.4 m/min; the diameter of the charge line in the anode nozzle is 2 mm; the distance from the place of introduction of the powder to the section of the nozzle - 4 mm; the axis of the plasma jet is perpendicular to the axis of rotation of the sample. Modes of gas flame melting of self-fluxing alloys after plasma sputtering are set within the following limits: oxygen pressure, MPa - 0.4-0.6; acetylene pressure, MPa - 0.02-0.04; oxygen consumption, l/min - 15-30; acetylene consumption, l/min - 107.

The conducted study of the structure and hardness of the coatings in the molten state, as well as after annealing and after hardening showed that the fused coatings are mainly characterized by a good density, although slightly less than the PGSR coating without chromium carbides.

The increase in porosity is due to the fact that single large pores or even their accumulation are observed in some areas at the boundary of the layer and the base metal. It is obvious that these areas

Of which have a poor connection with the matrix in the sprayed state. Larger accumulations of gases in such places do not have time to diffuse to the surface and coagulate in place.

The drawing shows the structure of the fused layer. In all coatings, the structure of the layer is heterogeneous in depth and two zones are observed: in one, connected to the substrate, the oriented columnar dendritic structure of the cast metal is clearly defined; in the other, the structure is more uniform, without noticeable orientation. After etching, three zones with different metallographic structures are defined in the layer:

And - the zone of the layer reaching the surface is characterized by a uniform distribution of homogeneous secretions;

II - the middle zone, which is characterized by non-homogeneous allocations in size;

And - the zone of the layer adjacent to the substrate has a dendritic structure.

The noted structure of the layers is due to the features of their melting by surface gas-flame heating.

The use of remelting allows you to significantly increase the density of the coating, excellent connection with the substrate. The porosity of the fused coating is approximately 1.3 95.

The wear resistance tests conducted showed a significant increase in the wear resistance of piston rings operating under friction conditions with high shock loads and abrasive wear, the results of which are shown in table. 2.

It follows from the obtained experimental data that the coating with Mi-S-51i-B alloys significantly increases the wear resistance of the products, while reducing the wear of the joint of the part.

The addition of chromium carbides increases the wear resistance of the coating more than three times compared to Z38ХО steel. Hardening of coatings with the formation of chromium carbides slightly reduces the wear resistance of the coating, but still leaves it at a fairly high level.

The use of the proposed composition of the coating and the method of obtaining the coating on the piston rings allow to increase the productivity and simplification of the technological process, increase its environmental friendliness, as well as increase the wear resistance of the obtained coating as a result of increasing its adhesion and increasing the thickness of the coating while ensuring high quality. Due to this, cost reduction, environmental friendliness of the process, increase in durability and service life of piston rings at high values of operational parameters are achieved. According to this useful model, tests were carried out regarding the implementation of the developed method of obtaining a coating on piston rings,

which confirmed its efficiency, high efficiency of the claimed method and obtaining the expected technical result and positive effect. The developed method of coating piston rings of internal combustion engines was implemented at the Malyshev Factory. The proposed method of obtaining a coating on piston rings can find effective application in mechanical engineering for obtaining a wear-resistant coating on various parts.

Table 1

The chemical composition of cast iron for the production of cast iron piston rings! C | 5 | Mp | St | M | Mo | Si | Mo | R | 5/ ch25 |32-34|141.710609| - | - | - 1 - | - | "03 | «olBi vch42 | 3.4-3.7 | 2.1-2.5 |0.85-1.3 1.2-1.5 | 0.6-0.9 | 0.3-0.4 | 0.03-0.1

Table 2

Results of wear resistance tests

Z8KHS steel

PGORA 0.247 0.136

PGSRAchAO 95 StzS2 0.102 0.089

PGORAchnaO 96

Claims (1)

- USEFUL MODEL FORMULA A method of strengthening the working surfaces of piston rings of internal combustion engines, which includes preliminary abrasive blasting of the surfaces for a certain time with silicon carbide with a particle size of 1.3-1.6 mm, followed by spraying a powder mixture, which is characterized by the fact that during the application of a heat-resistant wear-resistant coating on cast iron and steel parts, which includes air-plasma spraying of a layer of the Mi-S-St-5i-V-Ee composition (nickel - base) at I-280-320 A, 0-40-50 B, the spraying distance is 100-120 mm and constant parameters: sample rotation speed - 45 rpm, linear speed of sample movement relative to the plasma jet - 18.4 m/min; the diameter of the charge line in the anode nozzle is 2 mm; the distance from the place of introduction of the powder to the section of the nozzle - 4 mm; the axis of the plasma jet is perpendicular to the axis of rotation of the sample, with subsequent gas-thermal melting of the surface, before plasma spraying, abrasive jet treatment with silicon carbide with a particle size of 1.1-1.3 mm is carried out, and spraying is carried out from a self-flowing mechanical powder mixture, which additionally contains chromium carbide , with the following ratio of components, weights. 9: carbon 0.6-1.4, chromium 12-20, silicon 2.4-4.8, boron 2.0-4.3, iron 3-7, nickel - the base, as a result of which on the surface of the parts they form wear-resistant coating with a thickness of 180 to 200 microns, depending on the size of the part and its operating conditions. ON he nin non nn V VK V OH OK nn ZK V mno KV NI a pk o o o i a h A pe zho KK M Sya that OV KO du Ж ve i shCHOH DK dya MK ЖЖ Z NN i eh Kva she . sashe nn MO OKO v o ne sho kas B sh ok . p. Y Ol KK sh WHOOZ OO o NN i i p t ek v Ov i NY B a OO o M NN NN NYA KU OKKO i Vv i i V SHE NYA po. I. on koku, EOM ON MO is M . ЖК gts o S HO VN a Vu KK M KO t KK I sho 5 SHA ko en sho m v o o I She she o ne ee v s NE I Ash ih shaf B kon vh, TAM g v M Kk i V B g more KE I Eh Shh Ky OE Z SYA i ZONI Z eV x zha ne" a NE Z zen z a m NI sho she; che KO oz a o o i z a v ech ny poka i ne a OO a a KK se ovo DOV yah. until I tell the story "Zh Y UN Zhe km hnu OKO vale v i o IN v SHOK in i ne Y g Mo Ka OK a V KK odi Ah staff yo EN V sa OKO i nn o i ON shchi o o o i y NI a MNN ng she rom our v ON Z j ee aa v A Y J J i o i ik o VKA zhyuya vu o NI NN Ko YN I OO et ne V o an i i NN p i. ОО and ИЙ gen With Fr. OO. sok o o o NN v p, o v p M KK LV OV VO -