Complete List: What's New At Quantachrome?
DiaPac LLC, a Houston-based tungsten carbide processor, has switched to using Quantachrome Instruments' Autotap for their packing density, or tap density, measurements on high density powders which are custom blended for 'wear applications' such as oilfield drilling bits, mining tools, and milling equipment hardfacings. Their Chief Metallurgist explains the importance of tap density (TD) in terms of powder blend characteristics: "...particle size distribution and packing density (TD) dictate the tradeoff between wear resistance and toughness in the resulting metal matrix composites. We're always trying to increase wear resistance without sacrificing toughness, and both are sensitive to packing density (TD)."
Regarding the benefits that the Autotap brings to his department, he goes on to say "compared to our other TD machine, which has been the standard in our industry for as long as I know of (20+ years?), what initially appealed to me about the Autotap was the rotation during tapping - our blends often have very fine 'clingy' components, and we're often maximizing packing density, hence our materials can have high repose angles, and the 'climb' in the cylinder we used to get was more than we liked; we knew it cost us accuracy."
On the practical side, the tecnicians performing the TD test also noticed an improvement: "... they noticed immediately upon switching instruments how quickly and easily placing and removing the cylinder was in comparison to the other machine," and "...between not having to tap the cylinder side to level the powder bed, and not having to work the shroud mechanism, we don't break nearly as many of those expensive certified cylinders any more."
The Autotap conforms to ASTM B527 (Standard Test Method for Determination of Tap Density of Metallic Powders and Compounds) and a number of other international norms, and is available in one- and two-sample versions.