Under microscopy, the molybdenum surface reveals heavy contamination with dark oxide particles and oily residues. This causes pitting and rough texture, degrading its smoothness and integrity.

After Treatment

Using laser cleaning, molybdenum surfaces restore to a smooth, contaminant-free condition. This surface, it shows uniform texture and no residue, demonstrating high restoration quality. Material integrity stays intact, with original strength and conductivity preserved for general applications.

Molybdenum Laser Cleaning FAQs

What are the best laser parameters (wavelength, power, pulse duration) for cleaning oxides and contaminants from molybdenum surfaces without damaging the base metal?

For molybdenum's high reflectivity and melting point, I recommend 1064 nm wavelength with nanosecond pulses at 5.1 J/cm² fluence. This effectively ablates oxides while the 10 ns pulse width minimizes thermal diffusion, preventing micro-cracking in the 2623°C base metal.

How do you safely remove the white, powdery molybdenum oxide (MoO3) with a laser, given its low sublimation point and potential health risks?

To safely remove MoO₃, use a 100W nanosecond laser at 5.1 J/cm² to ablate the oxide while minimizing heat. Crucially, this process demands industrial fume extraction with HEPA filtration, as the oxide sublimes near 700°C, creating hazardous, inhalable particles that require operator respiratory protection.

Can laser cleaning be used to prepare a molybdenum surface for welding or brazing, and what surface quality (Sa) is achievable?

Laser cleaning effectively prepares molybdenum for welding by removing oxides and hydrocarbons using ~5.1 J/cm² fluence. This creates a chemically active surface, achieving a final roughness (Sa) typically below 1.0 µm, which is ideal for subsequent high-integrity brazing.

Why is molybdenum sometimes difficult to clean with a fiber laser, and are there advantages to using a green or UV laser instead?

Molybdenum's high reflectivity at 1064 nm makes standard fiber lasers inefficient. Green or UV wavelengths achieve much higher absorption, enabling effective cleaning at lower power—around 100 W—with minimal thermal impact on the substrate.

What is the risk of creating micro-cracks or a hardened layer on molybdenum components during laser cleaning?

Proper pulse control with 10 ns duration and 5.1 J/cm² fluence minimizes thermal stress. This prevents micro-cracking in molybdenum, which is prone to brittleness, by limiting the heat-affected zone and avoiding surface hardening.

After laser cleaning, how quickly does molybdenum re-oxidize, and are there recommended passivation methods to prevent this?

Freshly laser-cleaned molybdenum re-oxidizes rapidly in air, forming a thin layer within minutes. For long-term stability, handle components under inert atmosphere or apply a passivation treatment immediately after processing with your 1064 nm laser system.

Is laser cleaning suitable for delicate molybdenum parts, like thin foil, wire, or sintered components, without causing distortion?

Laser cleaning is suitable for delicate molybdenum components, but precise control is critical. For thin foils or porous sintered parts, use a low-power, high-speed strategy—around 100 W average power with a scan speed of 500 mm/s—to minimize heat input and prevent thermal distortion. Proper fixturing is also essential to manage thermal stresses.

What are the key differences in laser cleaning molybdenum compared to more common metals like steel or aluminum?

Molybdenum's high 2623°C melting point and brittleness demand precise fluence control near 5.1 J/cm² to avoid thermal stress cracking, unlike more forgiving steel or aluminum. Optimal cleaning requires a 100W, 1064nm laser with rapid 500 mm/s scanning to manage its reflectivity and prevent substrate damage from excessive heat input.

How do you verify the effectiveness of laser cleaning on molybdenum, and what analytical methods are used to check for residual contamination?

We verify molybdenum laser cleaning effectiveness first by visual inspection for a restored metallic luster. For quantitative analysis, XPS is essential to confirm the removal of oxides and quantify residual carbon below 5 at%, while a contact angle test assesses the surface's restored hydrophilicity.