Metal powder and alloy samples present unique challenges for elemental analysis. ColdBlock sample digestion technology solves these persistent challenges, achieving accurate, repeatable results. In this webinar, we demonstrate how ColdBlock delivers the consistency your lab demands across a range of sample types, with significantly faster digestion times compared to conventional methods.
This Q&A offers additional insights into the process of preparing metal powder & alloy samples using ColdBlock technology. If you have further questions, please contact us at info@coldblock.ca.
A great example is Höganäs, the Swedish company recognized as the world’s leading producer of metal powders. After integrating ColdBlock into their lab workflow, they reported benefits across three areas: speed, safety, and data quality.
Digestion times dropped significantly, improving throughput without sacrificing accuracy. They also noted reduced acid volumes and fume exposure — a meaningful win for lab safety. And critically for a precision manufacturer, trace and major element recoveries in their metal powder samples remained consistent and reliable throughout.
For any lab working in powder metallurgy or alloy characterization, Höganäs is a strong example of the benefits realized when using ColdBlock.
The first consideration is reactivity. For reactive matrices like ferrochrome, we use 0.1 g specifically to control the exotherm, scaling to 5 g in a sulfuric, hydrofluoric, nitric system would be dangerous and methodologically wrong. Sample mass isn’t arbitrary; it’s optimized for each matrix.
For less reactive matrices such as nickel superalloys, stainless steel, titanium, there’s no thermodynamic reason why larger sample masses would hurt recovery. The IR heating is consistent across the vessel and the acid volume can be proportionally increased.
Next is precision. Going from 0.1 g to 5 g actually improves precision in most cases because you’re reducing sub-sampling error. That’s one of the key advantages of ColdBlock. A 0.5 g microwave sample of a heterogeneous ferroalloy powder has significant sub-sampling uncertainty baked in. A 2 g ColdBlock sample of the same material has four times the statistical representation of the bulk. Your measurement precision might actually get better with larger masses because you’re averaging over more of the material.
Acid volume, digestion time, and power settings all need to be reoptimized when you significantly change sample mass. A method validated at 0.25 g doesn’t automatically transfer to 2 g. You need to confirm complete dissolution at the new mass. That’s good analytical practice for any digestion system.
Please note – 5 g is a system capability. For each matrix, the optimum sample mass is what the chemistry dictates, not what the vessel can physically hold. But when the chemistry allows larger masses, ColdBlock gives you that option.
High chromium matrices in ICP-OES are difficult – Chromium has over a thousand emission lines and when you’re measuring vanadium, manganese, or phosphorus in a 60% chromium ferrochrome digest, you are essentially trying to find a needle in a haystack where the haystack is also made of needles. And tungsten? Tungsten makes chromium look simple. We could spend a full day just on wavelength selection, interelement correction factors, and background correction strategies for these matrices and we’d still have more questions.
So, this question may require another webinar to properly respond. If there’s appetite for a webinar specifically on the analytical side of metals analysis by ICP-OES and ICP-MS, we will absolutely host it.
For now, we can say that analysis and associated considerations are the same with ColdBlock as they are with microwave or hot block. There are no differences in how you deal with analyisis. Matrix matching is everything. This includes matching the acid as well as the bulk of the matrix itself.
The sample we used was a cemented carbide cutting tool insert – tungsten carbide cobalt composite with titanium carbide and tantalum and niobium carbide secondary phases. This is actually a harder dissolution challenge than straight tungsten carbide -cobalt because titanium carbide and tantalum carbide are very refractory. Getting complete recovery of titanium, tantalum, and niobium, alongside tungsten and cobalt gives us confidence the method handles multiple phases. We would not yet claim it generalizes to every cemented carbide grade, but the multi-phase result is more meaningful than straight tungsten carbide cobalt would have been.
Yes – and that’s exactly the right question to ask.
We ran pure tungsten carbide – no binder, no secondary phases – through the same ColdBlock method. We recovered 97% tungsten by ICP-OES.
Now here’s the stoichiometry that makes that number meaningful. Pure WC is 93.8% tungsten by weight – the remaining 6.2% is carbon, which ICP-OES doesn’t measure. So, when you account for the fact that you’re measuring only the tungsten component of the compound, 97% recovery is essentially quantitative. The tungsten carbide phase itself dissolved. Not the binder dragging it along. Not a partial dissolution with fine particles settling at the bottom. The actual tungsten carbide grains went into solution.
That result, combined with the cemented carbide data where all analytes recovered at the manufacturers references values, gives us two independent lines of evidence that the WC phase dissolves, not just the surrounding matrix.
Looking at the data from the IARM Fe316LP-18 316L stainless steel reference material, the molybdenum recovery of 104% is performing exactly as expected and falls comfortably within the standard 90–110% acceptance interval. The measured average of 2.91 wt.% against a certified value of 2.81 ± 0.05 wt.% places the result squarely within the certified uncertainty band, and the 0.5% RSD across triplicate analysis reflects excellent method precision and reproducibility.
The marginal high bias observed in molybdenum is consistent with a well-documented, minor spectral interference effect from the dominant iron matrix (~63% Fe in 316L SS) on molybdenum emission lines in ICP analysis – a subtle but expected phenomenon in high-Fe alloy work. Importantly, this effect is small enough that it does not compromise data integrity or push results outside acceptance criteria.
Across all ten elements reported, recoveries range from 93% to 104%, demonstrating that this ColdBlock dilute HNO₃/HF digestion method is robust, reliable, and well-suited for the full elemental suite in 316L stainless steel – including the tight-tolerance compositions demanded by aerospace and defense applications.
You’re right. Nadcap-accredited labs test exactly these materials, at exactly this scale, and they’d benefit enormously from the throughput, the sample size flexibility, and frankly from not having to deal with pressurized vessels every day.
The reason they haven’t adopted it yet isn’t because the data isn’t there. It’s because Nadcap qualification is a process – a deliberate, rigorous, time-consuming process that exists for very good reasons. When you’re qualifying aerospace components, you don’t switch your sample preparation method because you saw a compelling webinar on a Tuesday afternoon. You qualify the method, you audit the method, you lock the method, and that takes time.
What that means for us is that we’re at the beginning of that cycle, not the end of it. The application data we’ve shown you today; the independent LGC ARMI study, the cemented carbide result, is the foundation of a Nadcap-qualifiable method package. We’re building that package deliberately and with the right labs.
If you’re in or adjacent to a Nadcap environment, you are exactly the kind of partner we’d like to work with right now. Please reach out at info@coldblock.ca.
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ColdBlock Technologies Inc.
4551 Zimmerman Ave
Niagara Falls, ON L2E 3M5
info@coldblock.ca.
