Before exploring solutions, it is necessary to first clarify the root cause of wear — the hard particles (with a particle size usually ranging from 0.1 to 5 mm) such as quartz sand and metal oxides contained in the slurry will continuously scour, grind, and squeeze the three core components of the pump (piston, cylinder liner, and seal) during the pump's operation, forming "three-body wear" (particle + component + medium). Among them:
If the mating surface of the piston and cylinder liner is worn, the gap will increase, leading to "internal leakage", which directly reduces the pump's conveying pressure and flow rate;
Wear of the seal will cause "external leakage", which not only wastes slurry and pollutes the environment but also intensifies the corrosion and scratching of the piston;
Long-term wear will also lead to increased vibration of components, triggering chain failures such as abnormal pump noise and bearing damage, and may even force the pump to shut down.
Therefore, material selection must focus on "wear resistance, corrosion resistance, and high strength", while pressure matching must focus on "adapting to working conditions and avoiding overload". Only the combination of the two can fundamentally reduce wear.
Wear of ceramic slurry piston pumps is concentrated on the piston, cylinder liner, and seal. Differences in working conditions of different components (such as movement mode, contact medium, and stress intensity) determine that the focus of material selection varies, requiring "matching based on needs".
As the "power execution end" of the pump, the piston needs to perform high-frequency reciprocating motion (usually 10-30 times per minute) inside the cylinder liner, while withstanding the scouring of slurry and high pressure (usually 10-30MPa). Therefore, the material must meet the requirements of high hardness, high toughness, and low friction coefficient to avoid fracture or excessive wear.
The cylinder liner and piston form a "dynamic seal pair". Wear on its inner wall directly affects the sealing effect and the service life of the piston. The hardness of the cylinder liner material must "match" that of the piston (to prevent scratches by the piston due to excessively low hardness, or accelerated piston wear due to excessively high hardness), while also having good erosion resistance.
The seal is the "key to leak prevention". It needs to be in contact with both slurry (abrasive) and hydraulic oil (lubricating), and maintain elasticity during the reciprocating motion of the piston to avoid seal failure due to wear. The material failure modes of seals are mostly "lip wear" and "hardening and cracking", so materials with wear resistance, oil resistance, and aging resistance should be prioritized.
- For conventional neutral slurries (e.g., ceramic raw material slurries), polyurethane seals are preferred (excellent wear resistance and high cost-effectiveness).
- For oil-containing or slightly corrosive slurries, nitrile rubber (NBR) is recommended.
- For highly corrosive or high-temperature slurries (e.g., acidic mine wastewater), fluororubber (FKM) or PTFE + elastomer composite seals should be selected (PTFE for corrosion resistance + elastomer for pressure retention).
- During seal installation, wear-resistant grease (e.g., molybdenum disulfide grease) must be applied to avoid dry friction.
The "pressure" of a ceramic slurry piston pump includes two key indicators: system working pressure (the pressure the pump needs to output, matching pipeline resistance and process requirements) and pump rated pressure (the maximum pressure the pump is designed to withstand). If the pressures are not matched, it will at best accelerate wear and at worst cause component rupture.
A higher working pressure is not always better. Excessively high pressure will increase the extrusion force between the piston and cylinder liner, doubling the wear rate; excessively low pressure, on the other hand, will fail to meet conveyance requirements. The actual required pressure must be calculated based on "slurry characteristics + pipeline system", with reference to the following formula:
Working Pressure P (MPa) = Slurry Specific Weight γ (kN/m³) × Conveyance Height H (m) / 10 + Pipeline Frictional Resistance Loss ΔP (MPa) + Local Resistance Loss ΔP’ (MPa)
The pump’s rated pressure must be higher than the actual working pressure to leave a "safety margin" (preventing component damage from instantaneous pressure peaks). However, the margin should not be excessively large – an overly large margin will lead to the pump operating in an "oversized pump for low load" state, resulting in low efficiency and accelerated wear.
Even if pressures are matched, frequent fluctuations in system pressure (e.g., sudden opening/closing of valves, uneven slurry concentration) will cause instantaneous changes in the force on the piston, leading to "impact wear". The following measures are required to control fluctuations:
- "The purer the ceramic material, the better": A purity of 100% is not optimal for alumina ceramics. 95% alumina ceramics have better toughness than 99% ones and are more suitable for working conditions involving impact. Excessive pursuit of purity will instead make them prone to fracture.
- "Choosing expensive seals is always right": PTFE seals have strong corrosion resistance but poor elasticity. If the slurry pressure is low (<5MPa), polyurethane seals are more cost-effective and provide better sealing performance.
- "The higher the pump's rated pressure, the safer it is": An excessively high rated pressure (e.g., choosing a 10MPa pump when only 5MPa is actually needed) will cause the pump to operate in a low-efficiency range. The reciprocating speed of the piston will be too fast, and wear will instead be accelerated.
- "Ignoring the fitting clearance": An excessively large fitting clearance between the piston and cylinder liner (>0.05mm) will lead to internal leakage, while an excessively small one (<0.01mm) will cause "seizure". The clearance needs to be adjusted according to the thermal expansion coefficient of the material (ceramics have a low thermal expansion coefficient, so the clearance can be slightly smaller).
- "Only replacing components without checking pressure": If pistons and seals need to be replaced frequently, it is necessary to first check whether the system pressure exceeds the rated value, rather than simply upgrading the material.
- Analyze working conditions: Clarify the particle hardness, concentration, corrosiveness, and temperature of the slurry;
- Select the right materials: Piston (wear-resistant + adaptable) → Cylinder liner (hardness matching the piston) → Seal (medium-resistant + elastic);
- Calculate pressure accurately: Calculate the actual working pressure → Match the pump's rated pressure (with a 1.2-1.5x safety margin);
- Control fluctuations: Install accumulators and stabilize slurry concentration to reduce impact wear;
- Conduct regular maintenance: Inspect seal wear weekly, measure fitting clearance monthly, and calibrate pressure gauges quarterly.
Through the dual control of "high-quality materials + reasonable pressure", the wear rate of ceramic slurry piston pumps can be reduced by more than 50%, and the service life of the equipment can be extended to 8,000-15,000 hours. This significantly reduces operation and maintenance costs and avoids production interruptions caused by wear.
