Hiilivety

Hiilivety is a proposed material property used in carbon-rich materials science to describe the propensity to form volatile carbon-containing species during thermal treatment. The concept is intended to capture devolatilization behavior that is not fully described by composition alone. The term is a neologism formed from the Finnish word hiili ("coal" or "char") and the English suffix -ety, reflecting its focus on volatility-like behavior of carbon-rich substances.

It is typically quantified under controlled pyrolysis conditions by measuring the rate and total amount of volatile products evolved as temperature increases. Practical reporting often uses the mass loss associated with volatiles per unit mass of sample, sometimes normalized by heating rate or by a reference sample, yielding indices such as a devolatilization rate or a hiilivety index. Analytical techniques include thermogravimetric analysis with evolved gas analysis (TGA-EGA), Pyrolysis-GC/MS, and online mass spectrometry.

Factors affecting hiilivety include the carbon content and its chemical form, hydrogen-to-carbon ratio, presence of heteroatoms, porosity and microstructure, particle size, and the atmosphere and heating rate during measurement. Catalytic impurities and the physical state of the sample can also alter the evolution profiles of volatiles.

Potential applications lie in coal processing, activated carbon production, and the thermal design of carbonaceous materials such as electrodes and carbon fibers, where devolatilization behavior influences energy requirements, porosity development, and material integrity. Because it is not yet a standardized property, hiilivety remains a descriptive tool rather than a universally adopted metric.

See also: devolatilization, pyrolysis, evolved gas analysis, carbonization.