Gas pycnometry and BET surface area each report a single number. X-ray micro-CT builds a three-dimensional map of the pore network, showing connectivity, tortuosity, and closed porosity that single-value tests cannot resolve, within real resolution and sample-size limits.

AIR7359 explains why AMS-AM metal powder feedstock specifications leave certain properties uncontrolled, citing limited applicability and immature standardized inspection methods, and what that gap means for aerospace AM qualification programs.

Powder spreading in powder bed fusion is a recoater-powder interaction shaped by cohesion, particle size distribution, and particle shape. This article maps streaking, short-feeding, and layer non-uniformity back to their underlying mechanisms and separates powder-driven causes from blade wear and spreading speed.

Dynamic and aerated powder testing measures basic flow energy and specific energy to fill the gap between shear cell consolidation data and Hausner ratio screening, particularly for fluidized processing and rapid-refill feeding.

Single-contact electrification apparatus measures charge transfer from one controlled particle-surface or particle-particle contact, isolating a variable that bulk triboelectric and charge decay measurements can only report as an average.

As aerospace metal additive manufacturing capacity expands, more reused powder is going back into qualified builds. The virgin-to-reused blend ratio decision depends on PSD shift, satellite formation, and morphology drift, and cannot be settled by a single powder check disconnected from the part's stress state.

Two lots that pass the same incoming flowability spec can still granulate differently after roller compaction. The reason usually traces to ribbon density, which responds to roll force, gap width, and feed screw speed as an interacting set, not to roll pressure in isolation.

Dense-phase and dilute-phase pneumatic conveying create different particle contact mechanics, and the resulting attrition and segregation risk depends on velocity, solids loading ratio, and the powder's own attrition sensitivity, not on a fixed assumption about which mode is gentler.

Talc's expected EU restriction is forcing cosmetic formulators toward mica, kaolin, silica, and starch. None of them reproduce talc's platelet slip, oil absorption, and low dustiness at the same time, and each substitution changes flow and compaction behavior in pressed powder products differently.

Cement fineness is not a single number. Blaine surface area, particle size distribution, grinding aid chemistry, and moisture history each pull on hydration reactivity in different ways, and a fineness specification that ignores any one of them will eventually let a bad batch through.

Geldart classification, minimum fluidization velocity, bubble dynamics, droplet-to-particle size ratio, and permeability all determine whether a fluidized bed process delivers controlled granule growth, uniform coating, or consistent drying at production scale.

Rotary airlocks function as pressure boundaries as much as metering devices. The rotor tip clearance governs particle attrition at the nip zone and the rate of fine-particle bypass under differential pressure. As clearance widens through wear, the downstream particle size distribution shifts in a pattern frequently misread as upstream process variation.