Laser-Clad Coating Doubles the Life of Coal-Cutting Picks in Mine Trials

Every coal miner knows the sound of a shearer at work: a relentless, grinding roar as rows of hardened steel picks bite into the coal face. What most people never hear is the quieter, costlier story of failure. In longwall mining, the cutting picks mounted on a shearer drum are consumables on a brutal schedule, and one of the most common ways they die is also one of the most preventable in principle: the tungsten carbide tip, brazed onto the steel body of the pick, snaps off or falls away entirely. Once that tip is lost, the exposed steel wears rapidly, cutting efficiency collapses, and the pick must be replaced, often long before its designed service life. A new study published in Scientific Reports by O. Eshaghian and S. H. Hoseinie of the Department of Mining Engineering at Isfahan University of Technology, together with H. Salimi Jazi of the Department of Materials Engineering, proposes a radical answer: get rid of the tungsten carbide tip altogether, and instead build the wear resistance directly into the pick’s surface with a laser-assisted coating process.

The idea sounds almost heretical. Tungsten carbide has been the gold standard for cutting-tool tips for decades precisely because it is extraordinarily hard and resists abrasion from rock and coal far better than any steel. But the braze joint that attaches a carbide tip to a steel pick body is a structural weak point. Under the shock loading of cutting hard coal seams, that joint experiences cyclic stresses, thermal gradients, and impact loads that can crack the braze or fracture the brittle carbide itself. When the tip detaches, it is not a gradual failure but a sudden one, and it often takes the pick out of service immediately. Worse, a lost tip can damage neighboring picks and even create safety hazards as loose carbide fragments circulate through the cutting zone. The Iranian research team reasoned that if the tip could be eliminated and the hard material integrated into the pick structure itself, the dominant failure mode of shearer picks could be engineered out of existence.

Their solution relies on a coating technology more commonly associated with aerospace components and turbine blades than with coal mining: laser cladding, applied specifically through the Plasma Transferred Arc, or PTA, method. In this process, a powdered feedstock material is melted by a concentrated, high-energy heat source and deposited onto the surface of the pick tip, fusing with the substrate to form a metallurgically bonded layer. The researchers chose a nickel-boron-silicon-iron alloy matrix, known as NiBSiFe, loaded with 60 percent tungsten carbide particles, and engineered at the nanostructure level. The nickel-based matrix provides toughness and thermal compatibility with the steel body, while the dense dispersion of tungsten carbide particles delivers the extreme hardness needed to resist abrasive wear. Because the coating is fused to the pick rather than brazed to it, there is no discrete joint to fail, no interface where a crack can initiate and propagate.

The materials science here is worth unpacking. Nickel-based self-fluxing alloys of the NiBSi family are prized in hardfacing applications because they form hard boride and silicide phases within a ductile nickel matrix during solidification, giving a composite microstructure that balances hardness with crack resistance. Adding tungsten carbide particles at a 60 percent loading pushes the composite toward the wear-resistant end of that spectrum, since the carbide particles act as the primary load-bearing phase against abrasive contact. The nanostructural refinement of the coating matters too: finer microstructures generally distribute stress more evenly and resist crack initiation better than coarse ones. The PTA process, which uses a plasma arc transferred between an electrode and the workpiece, offers precise control over heat input and dilution, meaning the coating can be deposited thickly enough to survive heavy wear without overheating the pick body and degrading the underlying steel’s mechanical properties.

Laboratory characterization alone, however, would not settle the question. The true test of a mining tool is the mine itself, and the team took their coated picks to one of the most demanding venues available: the shearer operating at the Tabas Parvadeh Coal Mine in Iran. There, the new-generation picks ran side by side with conventional picks of standard design, cutting real coal under real operating conditions. This kind of field comparison is rare and valuable, because laboratory abrasion tests on standardized wheels or slurry rigs cannot fully reproduce the impact loading, thermal cycling, and variable seam conditions that a shearer encounters underground. The researchers monitored the picks over a cutting distance of 12,000 meters, focusing their microstructural wear analysis on the pick tip region, the zone that governs both cutting performance and overall tool lifespan.

The results were striking. After 12,000 meters of cutting, the wear rate in the pick tip area was approximately 5 percent for the laser-cladded picks, compared with roughly 10 percent for the traditional picks. In other words, the final wear rate of the coated picks was about half that of the conventional design, which translates directly into a useful life approximately twice as long. For a mine operator, that doubling is not an incremental improvement; it is a step change in consumable economics. Fewer pick changes mean less downtime on the shearer, fewer spare parts consumed, reduced labor exposure during pick replacement, and more consistent cutting geometry at the coal face, which in turn improves machine efficiency and fragmentation quality.

Just as important is what the study found about failure modes. By removing the tungsten carbide tip from the conventional coal-cutting picks, the researchers report that the dominant problems caused by tip failure and tip loss were completely solved. There was no braze joint to crack, no brittle carbide block to shatter under impact, and no sudden detachment event to take the pick out of service prematurely. Instead, the coated picks degraded gradually and predictably through surface wear, the kind of failure a maintenance team can plan for. Predictable wear is arguably as valuable as reduced wear, because it allows mines to schedule pick replacement during planned maintenance windows rather than reacting to unexpected failures mid-shift.

The broader implications reach beyond a single coal mine. Shearer picks are used in enormous numbers across the global longwall mining industry, and pick consumption is a significant line item in operating costs, alongside the indirect costs of downtime and the safety implications of frequent manual replacement on the shearer drum. If a coating-based design can double pick life in the demanding conditions of Tabas Parvadeh, it offers a template that could be adapted to other cutting tools in mining and tunneling, from roadheader picks to continuous miner bits. The underlying principle, replacing a mechanically attached hard tip with a metallurgically fused hardfacing layer, is broadly applicable wherever brazed carbide tips suffer from joint failure under impact loading.

There are, of course, practical considerations that will shape adoption. Laser cladding and PTA deposition are more sophisticated and capital-intensive processes than brazing a carbide tip onto a steel blank, and the coated picks must be produced at a cost that the doubled service life can justify. The study, published open access on 12 October 2026 and carried out without external funding, focused on the microstructural and operational performance of the picks rather than a full economic analysis, so the commercial case will need to be built out through larger-scale trials. Coating thickness, deposition consistency, and repair or re-coating of worn picks are all engineering questions that industrial deployment will have to answer. Still, the field data from Tabas provide the crucial proof of concept: the concept works in the environment where it matters.

What makes this study compelling is its directness. Rather than trying to improve the braze joint, a path many researchers have pursued with marginal gains, the team removed the joint entirely and re-engineered the pick around a fused composite coating. The microstructural wear analysis confirms that a NiBSiFe matrix reinforced with 60 percent tungsten carbide, deposited by plasma transferred arc cladding, can stand up to 12,000 meters of real coal cutting with half the wear of a conventional pick. If the results hold up at scale, the humble shearer pick, one of the most heavily consumed tools in mining, may be on the verge of its most significant redesign in decades, and the mines that adopt it could see the benefits in their cost ledgers and their safety statistics alike.

Subject of Research: Laser-cladded nanostructured coatings for wear-resistant coal mining picks

Article Title: Microstructural wear analysis of laser cladded new generation mining tools

Article References: Eshaghian, O., Hoseinie, S. H., & Salimi Jazi, H. (2026). Microstructural wear analysis of laser cladded new generation mining tools. Scientific Reports. https://doi.org/10.1038/s41598-026-74560-x

Image Credits: AI Generated

DOI: 10.1038/s41598-026-74560-x

Keywords: laser cladding, plasma transferred arc, tungsten carbide, shearer picks, coal mining, wear resistance, NiBSiFe coating, nanostructure, hardfacing, Tabas Parvadeh Coal Mine, mining tools, materials science