Carbide Powder Suppliers

Industry Knowledge Expansion

Matching Particle Size to Process: Getting the Most from Carbide Powder

The same Carbide Powder can perform very differently depending on whether its size distribution suits the deposition process. HVOF and HVAF systems need fine, narrow cuts so particles fully heat and accelerate in a short dwell time. Laser cladding and PTA welding use coarser cuts, because the powder is fed into a melt pool and fine particles tend to be blown away or vaporized. A mismatch usually shows up as clogged feeders, low deposition efficiency, or an uneven coating surface.

• HVOF / HVAF spraying: typically 15–45 µm or 5–25 µm for thinner, denser coatings
• Plasma spraying: typically 20–63 µm
• Laser cladding: typically 45–125 µm, depending on the nozzle and feed rate
• PTA / plasma transferred arc overlay: typically 53–180 µm

When we produce powders for a specific process, we control both the D10/D50/D90 values and the fines fraction, so the powder feeds consistently from the first hour of a run to the last.

Choosing the Binder Matrix in Carbide Composite Powder

In Carbide Composite Powder, the hard phase (usually tungsten carbide) provides abrasion resistance, while the metallic matrix determines toughness, corrosion resistance, and how well the layer bonds to the substrate. Choosing the matrix is often more important than choosing the carbide fraction, and the table below summarizes the common options.

Because our range covers cobalt-, nickel-, copper-, and iron-based systems, we can tune the matrix and carbide ratio to your working conditions rather than forcing a standard grade to fit.

Controlling Carbide Dissolution in Laser Cladding Layers

When a tungsten carbide-containing Carbide Metal Powder is fed into a laser melt pool, part of the WC dissolves into the liquid metal. The released tungsten and carbon can re-precipitate as brittle phases such as W2C or M6C-type carbides, which increase cracking sensitivity and leave less carbide to resist wear. Dissolution is driven mainly by melt pool temperature and time at temperature, so process parameters matter as much as powder choice.

Practical ways to limit dissolution

• Use the lowest laser power that still gives full fusion with the substrate, and raise the scanning speed to shorten the melt pool lifetime
• Select larger carbide particles (for example 45–106 µm), since their smaller surface-to-volume ratio slows dissolution
• Consider spherical cast WC or a nickel-coated carbide, where the coating acts as a partial diffusion barrier
• Keep the carbide fraction in the 35–60 wt% range for most nickel-based claddings; higher loads raise the crack risk sharply

Why Powder Flowability Deserves More Attention Than Chemistry Sheets

Two batches of Carbide Composite Powder with identical chemical analysis can behave very differently in the feeder. Flowability depends on particle shape, surface roughness, moisture content, and the fines fraction. Spherical, agglomerated-and-sintered or gas-atomized particles typically flow well, while crushed and angular particles tend to bridge in the hopper and pulse at the nozzle. A pulsing feed creates thickness variation and local porosity in the finished layer.

A simple incoming inspection routine can prevent most feeding problems:

• Measure Hall flow rate (50 g through a standard funnel) and compare it with the previous batch that ran well
• Check apparent density and tap density; a large gap between the two suggests poor packing or excess fines
• Inspect a sample under a microscope for satellites, broken particles, and hollow spheres
• Record humidity in the feeding room, since damp powder can lose flowability within hours

Storing and Drying Alloy Powders Before Use

Fine metal powders absorb moisture from the air, and moisture causes clumping, unstable feeding, and hydrogen-related porosity in cladding and welding deposits. Keep sealed containers in a dry, temperature-stable room, and avoid opening a large drum repeatedly; decant working quantities into smaller sealed containers instead. Once a container is open, use it within a reasonable period and reseal it with fresh desiccant.

If powder has picked up moisture, drying at about 100–120 °C for 2–4 hours in a ventilated oven usually restores flow, then let it cool in a sealed container before use. Do not dry powders containing organic binders or coatings at higher temperatures without checking the manufacturer's data. Our powders are supplied in sealed packaging, and we are glad to advise on the correct pre-treatment for your equipment.

Troubleshooting Cracks and Porosity in Carbide-Reinforced Coatings

Cracking and porosity are the two most common defects in carbide-reinforced layers, and they usually come from a small number of causes. Cracks form when thermal stress exceeds the strength of the matrix, especially with high carbide fractions or a large hardness gap between coating and substrate. Porosity comes from trapped gas, damp powder, or insufficient melt pool stability.

Cracks

• Preheat the substrate (200–400 °C is common for steel, depending on grade) to reduce the thermal gradient
• Use a tougher, nickel-rich buffer or transition layer between substrate and high-carbide top layer
• Slow the cooling of large parts with insulation or a controlled post-heat

Porosity

• Dry the powder and clean the substrate of oil, rust, and moisture before starting
• Check the shielding and carrier gas flow; excessive carrier flow can disturb the melt pool and entrain air
• Reduce scanning speed slightly if gas has no time to escape before solidification