PCGH Gear Carbonite Ultra review – Generally not bad but with question marks

1 - Introduction and technical data 2 - Test methodens, the ASTM 5470-17 standard and equipment 3 - Thermal resistance 4 - Thermal conductivity and real-world simulations 5 - Material analysis and microscopy 6 - Summary and conclusion

Microscopy and material analysis

Let’s start with the microscopy. It is quite interesting to observe how a paste can be spread and when it de facto tears on and off the glass substrate. You can see that the Carbonite Ultra adheres very well, but cannot be peeled off endlessly without tearing off. The heels are rather unsightly and the paste also pulls disgusting threads. This is probably due to its composition, as there is too much silicone oil. The matrix used (polysiloxanes) is rather thin and the final consistency is mainly achieved by the fillers. I would have preferred to see a firmer matrix and less “sludge” from fillers to thicken the paste. It is also even more extreme than the Arctic MX-6.

The risk of outgassing or bleeding of the silicone base is unfortunately real here. This is also where my concerns about the long-term durability at high temperatures come in. If I can pull the paste apart mechanically like this, then it is certainly no different under heat and pressure. We’ll have to see how well it all performs after 6 to 9 months. However, I am already working on an ageing test. The paste should be history in a year at the latest, if not much sooner.

In addition to the organic colorants, there are unfortunately also a lot of darker inclusions, which indicates a rather below-average mixing and production quality. My guess here is contaminated and slightly clumped zinc oxide.

Now let’s take a closer look at what’s in it and what’s not. The paste contains a lot of fillers, mainly very fine zinc oxide. The aluminum oxide content is rather low, but still sufficient. The paste benefits from its rather thin consistency, but this is likely to break its neck in the long-term run.

Finally, I want to analyze one of the darker inclusions and yes, it is zinc, but clumped and discolored.

Test equipment for the material tests, accuracy and test preparation

The material testing and measurement of the pastes and pads is carried out by my Keyence VHX 7000 with EA-300, which enables 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 is a huge time saver. 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 distinct advantages.

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 today they are not useful 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)