Abstract: This paper discusses the oxyacetylene thermal spraying technology and uses domestically produced new wear-resistant materials for the spray repair of large and heavy-duty sliding bearings. Through experiments, it was found that the anti-wear and anti-wear properties of the bearings repaired using this method were significantly improved, and the load-bearing capacity was greatly enhanced, playing a role in strengthening the repair process. This repair method has simple equipment and process, easy construction, low cost, high efficiency, and is easy to master. It is a process worth promoting.

Keywords: thermal spraying technology; Sliding bearings; repair

1. Problem posing

1.1 Traditional restoration methods

The price of purchasing large and heavy-duty sliding bearings is relatively high. When they are damaged, they should be repaired as much as possible, especially in the case of a lack of accessories. Repair becomes even more important.

The traditional repair methods for bearings made of different materials are shown in Table 1.

Table 1 Traditional repair methods for bearings made of different materials

1.2 Problem location

From traditional repair methods, it can be seen that they are limited to restoring the shape, size, and accuracy of bearings, and do not involve the issue of strengthening repair, thus failing to achieve a strengthening effect. The main shortcomings are: complex process, low productivity, high cost, poor repair quality, short service life, and low economic benefits.

1.3 Proposed New Repair Methods

Due to the many inherent shortcomings of traditional repair methods, the issue of how to use new materials, processes, and technologies to repair and strengthen bearings has been presented to us.

If the new method can meet the needs of advanced technology, simple process, high productivity, low cost, and good quality, not only can it ensure the original requirements in shape, size, and accuracy, but also achieve a strengthening effect, and is easy to master and promote, then this idea is successful.

2. Introduction to new repair methods

2.1 Overview

Thermal spraying technology is a rapidly developing new technology with broad prospects in surface protection, surface strengthening, and preparation of special surface coatings. Especially the oxygen acetylene powder spraying technology, which has the advantages of simple equipment, flexible process, and easy promotion; It is a practical technology with low cost, fast effect, large quantity and wide coverage, and significant economic benefits. It can make the surface of the workpiece have different properties such as wear resistance, corrosion resistance, and oxidation resistance according to different spraying materials. It can play a positive role in repairing mechanical wear parts, protecting corrosive media, adapting to high parameter working conditions, saving precious metal materials, improving product quality, and reducing costs.

2.2 Spray coating materials

The commonly used spraying materials and related properties for sliding bearings are shown in Table 2. The table (top) shows the standard reference sample, which is the upper sample quenched from 45 # steel; (Below) refers to the lower specimen with coating material.

Table 2 Common Spray Materials and Related Properties for Sliding Bearings

From Table 2, it can be seen that the average wear of samples with coating materials is one order of magnitude lower than that of samples quenched with 45 # steel; Both have high PV values.

2.3 Main equipment and auxiliary equipment

2.3.1 Main equipment

Oxygen cylinders and oxygen pressure reducers, acetylene cylinders and acetylene pressure reducers, spray guns, rubber hoses, etc.

2.3.2 Auxiliary equipment

Spray painting machine, sandblasting device, acetylene dryer, filter, powder feeder, etc.

3. Process

3.1 Surface preparation of workpieces

The purpose of preparing the surface of the workpiece is to clean and roughen the surface of the substrate to be sprayed, and to shape the surface appropriately, in order to improve the adhesion between the coating and the substrate.

a. Cleaning

Clean grease and other pollutants from the surface of the parts, usually using alkaline solution and solvents, or industrial gasoline.

b. Sandblasting

Use compressed air flow, pressurized water flow, or centrifugal force to impact abrasive (sand) particles on the surface of parts, removing rust, oxide scale, corrosion products, and other attachments. Sandblasting should try to maintain the jet perpendicular to the surface of the parts to avoid affecting the bonding strength between the metal and the substrate. For sandblasting treatment of sprayed workpieces, dry sandblasting should be applied.

c. Mechanical processing

Performing roughening treatments such as slotting and rolling on the surface of parts can effectively limit and disperse the shrinkage stress of coatings. The main purpose of mechanical processing is to make the shape of the sprayed surface of the part suitable for the formation of the coating and provide space for embedding the coating, which is conducive to spray processing and improving the stress state of the coating, enhancing the adhesion between the coating and the substrate as well as the coating itself.

d. Chemical treatment

Performing corrosion treatment on the repaired surface of the component can disperse many depressions more widely on the untreated surface, improving the bonding strength between the component and the coating.

e. Electric Hair Pulling

Lightly weld metal wires on the surface of metal parts to create small sputtered rough surfaces.

3.2 Preparation of Powder

a. Determine the powder grade based on the coating design.

b. Check if the powder grade meets the usage requirements.

c. If the agglomeration or poor flowability of the powder is caused by moisture absorption, the powder can be baked at a temperature of 120C for about 1 hour, and then sieved as required after cooling to room temperature.

3.3 Equipment Preparation

Check if the technical condition of the equipment and systems used is normal, and if there are any leaks in the pipelines.

3.4 Spraying

3.4.1 Preheating of workpieces

Preheating flame: neutral flame

Preheating temperature: 100~150 ℃

3.4.2 Parameter Control

Flame properties: neutral flame

Gas pressure: Oxygen 0.6~0.7MPa

Acetylene 0.04~0.045MPa

Spray distance: 250~280mm

Spray angle: 87 °~89 °

3.5 Measurement

Check whether the coating thickness of the repaired parts to be sprayed meets the design requirements after cooling.

3.6 Post coating processing

Determine the positioning and clamping position and machining quantity based on the shape and technical requirements of the bearing.

3.7 Inspection

Check whether the repaired dimensions meet the requirements of the original drawing design.

3.8 Combined tile grinding and scraping

Grind and scrape according to the contact point situation after tile assembly, until the contact spot reaches more than 85% of the contact surface and is evenly distributed.

4. Experimental results

Through bench tests, wear tests, hardness measurements, and bond strength tests, we have achieved the expected results.

5. Conclusion

a. Good coating performance. The alloy coating formed by powder spraying with oxyacetylene flame has the characteristic of multiple pores, with a porosity of about 20%. This porous coating can store oil and has oil storage properties. Compared with traditional metal alloy layers, its wear resistance and wear reduction have been greatly improved and enhanced.

b. Advanced technology. The oxyacetylene flame powder spraying equipment is simple, requires less investment, has quick results, is easy to operate, and is easy to promote; At the same time, it is a new technology with flexible process, convenient construction, and low pollution, which has great development prospects. Choosing this technology for the repair of large and heavy-duty sliding bearings is completely worth trying and promoting.

2026 September 1st Week Marginal Product Recommendation

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