Thermal Grizzly Kryonaut vs. Paste X (pre-series) in the thermal paste test: Changing of the guard after 10 years?

Microscopy and material analysis

It is very interesting to observe how a paste spreads and when it de facto tears up and down on the glass slide, because it also allows conclusions to be drawn about the mixture. But even the color shows the difference between the cryonaut (light) and paste X (darker) quite clearly.

I don’t have to enlarge the Kryonaut very much, because we can almost see a liquid that sticks everywhere and can be spread very thinly. This is certainly part of the success of this paste, because the skill level for an optimal application is quite low here.

Paste X is much more viscous, but it still adheres quite well. Thermal Grizzly has once again found an acceptable compromise here, which doesn’t come close to the Thermalright TF8, but makes handling much easier. And if we remember: the differences between Paste X and the TF8 are very small. The direct competitor would therefore be the Corsair XTM70, for example, which is rather unattractive in terms of price.

The risk of outgassing or bleeding of the silicone base is of secondary importance with Paste X. With the Kryonaut, on the other hand, I see a shelf life of 9 to 12 months before degradation becomes noticeable, but this also depends on the user profile and thus the cycles. A look at the enlarged paste shows a sea of very fine nanoparticles and some slightly larger particles. The smaller “pile” of aluminum oxide with 15 µm is therefore only a small lapse when mixing, but you will hardly get it really homogeneous anyway. However, this will disappear and is therefore only a marginal phenomenon.

Paste X contains significantly more aluminum oxide and is generally not as “slimy”. We also see a lot of nanoparticles (or don’t see them because they are too fine and hide in the matrix).

Let’s take a closer look at what’s actually in it and what’s not. In addition to all the silicone as a matrix, the paste also contains some fillers, mainly very fine zinc oxide and a little less aluminum oxide. The aluminum oxide content is lower, but still sufficient. The ZnO is primarily used as a gap filler between the somewhat larger (and also harder) Al2O3 grains. This makes the paste fluid, i.e. slippery.

Paste X has a completely different design because we see a completely different structure with many particles and predominantly aluminum oxide at the same resolution this time. The zinc content is significantly lower.

Test equipment for material tests, accuracy and test preparation

My Keyence VHX 7000 and EA-300 are responsible for material testing and measuring the pastes and pads, enabling both exact measurements and fairly precise mass determinations of the chemical elements. But how does it actually work? The laser-induced breakdown spectroscopy (LIBS) I used for this article is a type of atomic emission spectroscopy in which a pulsed laser is directed at a sample in order to vaporize a small part of it and thus generate a plasma.

The emitted radiation from this plasma is then analyzed to determine the elemental composition of the sample. LIBS has many advantages over other analytical techniques. Since only a tiny amount of the sample is needed for analysis, the damage to the sample is minimal. The real damage is caused in today’s article by my rather coarse cutting and separating tools. This still quite new laser technique generally requires no special preparation of the samples for material analysis. Even solids, liquids and gases can be analyzed directly.

LIBS can detect multiple elements simultaneously in a sample and can be used for a variety of samples, including biological, metallic, mineral and other materials. And you get true real-time analysis, which saves a tremendous amount of time. As LIBS generally requires no consumables or hazardous reagents, it is also a relatively safe technique that does not require a vacuum as with SEM EDX. As with any analytical technique, there are of course certain limitations and challenges with LIBS, but in many of my applications, especially where speed, versatility and minimally invasive sampling are an advantage, it offers significant benefits.

I would first like to point out that the results of the percentages in the overviews and tables have been intentionally rounded to full percentages (wt%, i.e. weight percent), as it happens often enough that production variations can occur even within the presumably same material. Analyses in the parts-per-thousand range are nice, but not very useful today when it comes to reliable evaluation and not trace elements. However, every day in the laboratory starts with the same procedure, because when I start, I work through a checklist that I have drawn up. This takes up to 30 minutes each time, although I have to wait for the laser to warm up and the room to reach the right temperature anyway.

• Mechanical calibration of the X/Y table and the camera alignment (e.g. for stitching)
• White balance of the camera for all lighting fixtures used
• Check alignment of LIBS optics and standard lens, calibrate alignment of laser to own optics (x300)
• Test standard samples of the materials to be measured and correct the curve if necessary (see image above)