Armstrong process

Lore & Background

The Armstrong process uses sodium as the reducing agent, which is liquefied and introduced in a combined stream with titanium tetrachloride. The chemical reaction produces titanium and sodium chloride at approximately 98°C. The resulting titanium powder has a unique coral-like morphology, differing from spherical gas-atomized powder, mechanically crushed angular particles, or the titanium sponge morphology from the Kroll process.

A 2016 paper by MacDonald et al. reported that the Armstrong powder is produced directly from the reduction of titanium tetrachloride 'in a continuous liquid loop', with a cost of 11-24 USD/kg, roughly an order of magnitude higher than the price of steel. The process was patented in 1999.

Reader's Guide

The Armstrong process represents a distinct approach to titanium refining, patented in 1999, that yields a powder with a coral-like morphology rather than the more common spherical or angular forms. Its continuous liquid loop method, as described in a 2016 paper by MacDonald et al., produces titanium directly from titanium tetrachloride reduction using liquid sodium. The cost of the resulting powder, 11-24 USD/kg, is noted as roughly an order of magnitude higher than steel, indicating both its specialized nature and potential economic considerations. The process's output can be sprayed into pattern-molds, suggesting applications in additive manufacturing or near-net-shape forming. While the Kroll process remains the dominant industrial method for titanium production, the Armstrong process offers an alternative that produces a distinct powder morphology, which may be advantageous for certain applications. The process's reliance on sodium as a reducing agent and its continuous operation differentiate it from batch processes like the Kroll method.

Did You Know?

• The Armstrong process was patented in 1999.
• Its output has a 'coral-like morphology', differing from spherical gas-atomized powder, mechanically crushed angular particles, or titanium sponge from the Kroll process.
• A 2016 paper by MacDonald et al. reported the powder cost at 11-24 USD/kg, roughly an order of magnitude higher than steel.
• The reducing agent is sodium, liquefied and introduced with titanium tetrachloride in a combined stream.