Zhuojin Pipe Fitting Co., LtdWear-Resistant Hardfacing Materials in Cement Industry Applications: Current Status and Development Prospects
Literature Overview
Wei Jianjun and colleagues from Zhengzhou Machinery Research Institute published this review in China Surface Engineering (2009, Vol. 22, No. 5), providing a comprehensive assessment of hardfacing technology applications across cement industry equipment. The paper examines operating conditions, failure modes, and the effectiveness of hardfacing overlays on compression rollers, vertical mill rollers, grinding discs, crusher hammer heads, and hammer plates. This review remains highly relevant today, as the fundamental tribological challenges in cement grinding and crushing operations have not materially changed.
Operating Conditions and Failure Modes Analysis
The cement industry presents some of the most severe abrasive wear environments encountered in industrial practice. The materials being processed—limestone, clay, gypsum, and clinker—are inherently abrasive, often containing quartz and other hard mineral inclusions. The following table summarizes the key operating conditions identified in the study:
| Component | Operating Speed | Material Hardness | Primary Wear Mechanism | Typical Service Life Without Hardfacing |
|---|---|---|---|---|
| Compression roller | 80–150 m/min | Mohs 6–8 (limestone/clinker) | Abrasive (two-body) | 2–4 months |
| Vertical mill roller | 40–80 m/min | Mohs 7–9 (clinker) | Abrasive + impact | 3–6 months |
| Grinding disc | 20–50 m/min | Mohs 6–8 | Abrasive (three-body) | 4–8 months |
| Crusher hammer head | 30–60 m/s impact | Variable | Impact-abrasive | 1–3 months |
| Hammer plate | 20–40 m/s impact | Variable | Impact-abrasive | 1–2 months |
The failure analysis reveals that wear is rarely uniform. Compression rollers exhibit localized wear at the nip zone where material is compressed and sheared between rollers. Vertical mill rollers show progressive surface recession with occasional spalling at high stress concentrations. Crusher components experience a combination of high-energy impact and subsequent abrasive wear, leading to a characteristic "rounded" degradation profile.
Hardfacing Materials and Process Selection
The study categorizes the hardfacing approaches into two principal strategies: composite manufacturing (designing the component with a wear-resistant overlay from the outset) and remanufacturing (applying hardfacing overlays to worn components to restore functionality).
Material Systems Evaluated
| Material System | Typical Hardness (HV) | Key Alloying Elements | Application Component | Performance Improvement |
|---|---|---|---|---|
| High-carbon martensitic | 450–550 HV | C 1.2–2.5%, Cr 8–12% | Compression rollers | 3–5× life extension |
| High-chromium cast iron type | 500–650 HV | Cr 20–30%, C 2.5–4.0% | Vertical mill rollers | 4–6× life extension |
| Carbide-composite (WC/Co) | 800–1200 HV | WC 50–70%, Co binder | Grinding discs | 5–8× life extension |
| Low-alloy impact-resistant | 300–400 HV | Mn 1.5–2.5%, Cr 0.5–1.0% | Crusher hammers | 2–3× life extension |
| Ceramic-reinforced composite | 600–900 HV | Al2O3 or SiC particles | Hammer plates | 3–5× life extension |
Process Considerations
The selection of hardfacing process is dictated by component geometry, production volume, and required overlay quality. For large cylindrical components such as compression rollers and vertical mill rollers, submerged arc welding (SAW) with flux-cored wire or strip-cored wire offers the best combination of deposition rate and dilution control. For complex geometries such as crusher hammers with thin sections and high curvature, SMAW or FCAW provides the necessary flexibility. The study emphasizes that dilution control is paramount: excessive dilution from the base material reduces the hardness and carbide content of the overlay, directly diminishing wear resistance.
Economic and Environmental Benefits
The economic analysis presented in the paper is compelling. For a typical cement plant processing 5000 t/d of clinker, the annual replacement cost for unworn compression rollers can exceed several hundred thousand dollars, factoring in both material costs and production downtime. With hardfacing overlays achieving 3–5× life extension, the annual maintenance budget can be reduced by 60–75%. Additionally, the remanufacturing approach reduces material consumption and waste generation, aligning with environmental sustainability objectives.
Development Directions and Reflections
The authors identify three key development directions that I believe remain valid today:
- Expansion of hardfacing application scope to additional cement equipment components beyond those currently addressed, including separator vanes, conveyor rollers, and kiln liner plates.
- Deeper investigation of wear mechanisms specific to each component, recognizing that abrasive, adhesive, and impact wear often coexist and require different material solutions.
- Development of materials that simultaneously optimize both wear resistance and crack resistance, as the trade-off between hardness and toughness remains the central challenge in hardfacing material design.
From my perspective, the most significant insight is the recognition that hardfacing is not a one-size-fits-all solution. The selection of overlay material must be matched to the specific wear mechanism, and this matching requires careful analysis of the operating conditions. In cement grinding operations, where three-body abrasion dominates, carbide-reinforced overlays outperform pure martensitic systems. In crushing operations where impact energy is the primary driver, tougher low-alloy systems with moderate hardness may actually outperform very hard but brittle overlays that are prone to chipping.