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Diapac, a supplier of custom tungsten carbide powder blends, has switched to using Quantachrome Instruments’ Autotap for packing- or tap-density measurements on high-density powders.

Diapac selected Autotap because of its improved accuracy and ease of use.

Diapac LLC, a tungsten carbide processor, has switched to using Quantachrome Instruments’ Autotap for its packing density, or tap density, measurements on high-density powders.

These are custom blended for ‘wear applications’ such as oilfield drilling bits, mining tools and milling equipment hardfacings.

Its chief metallurgist explained the importance of tap density (TD) in terms of powder-blend characteristics: ‘Particle size distribution and packing density (TD) dictate the trade-off 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).

‘Compared with our other TD machine, which has been the standard in our industry for more than 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 maximising 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.

‘The technicians 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 with the other machine.

‘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.

It is available in one- and two-sample versions.

It is used in a variety of industries, including catalysis, pharmaceuticals, pigments and food.

Quantachrome Instruments

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