Corrosion of ZrB₂ Powder During Wet Processing – Analysis and Control

Abstract

Corrosion behavior of ZrB 2 powder during wet processing in water or ethyl alcohol was studied both with and without an organic additive. Incorporation of oxygen and pH change did not intensively occur during static aging of aqueous slurries, but corrosion was enhanced when stirring the slurries. The oxygen content of the powder increased rather rapidly with milling time in ethyl alcohol. The molecular weight of polyethylenimine effected the pH change and oxygen content of ZrB 2 powder, after corrosion in water for 18 months. X-ray photoelectron spectroscopy analysis informed that the surface of both the pristine and corroded powders was mainly covered with ZrOH, but a certain amount of Zr-B bonding remained at the powder surface after the wet processing.

Properties of Slip‐Cast and Pressureless‐Sintered ZrB2–SiC Composites

“… ZrB 2 and SiC are the main components; Si 3 N 4 is the sintering aid; B 2 O 3 , ZrO 2 , and SiO 2 are originally present in the raw powders and also formed on the particles surfaces during the wet milling; 21 and carbon is a raw powder impurity and further carbon sources are the polyethylene bottles used during ball milling, binder, and sintering atmosphere; 6,22,23 many reactions occurred during sintering, changing the final composition and forming new phases. …”

“…B 2 O 3 , ZrO 2 , and SiO 2 are originally present in the raw powders and also formed on the particles surfaces during the wet milling; 21 and…”

“…Although having lower green density (Table III), slip‐cast samples are denser than cold isostatic pressed ones after sintering. This could be derived from the additional amount of oxygen introduced during the ball milling in water during the preparation of the slip; 21 a greater amount of oxidized phases (SiO 2 , B 2 O 3 ) increases the liquid phase quantity favoring sintering.…”

Novel synthesis of ZrB2 powder by low temperature direct molten salt reaction

“…Afterwards, the melt powder was washed several times by hot distilled water until no F -was detected in the washing solution by AgNO 3 . The obtained powder was subjected to acid leaching, using a dilute HCl solution to remove the aluminium and residual salts in consideration with ZrB 2 particles have no reaction with HCl [21]. The leached mass was washed repeatedly with hot distilled water until it was free of Cl - [22].…”

Dispersion and Rheology of Aqueous Zirconium Diboride Nanosuspensions

“…Unfortunately, when preparing aqueous ZrB 2 nanosuspension, nanoparticles easily form agglomerates owing to the large surface area and high surface energy. Research by a number of authors has just shown their interests in the dispersion behavior of ZrB 2 micrometer‐ and submicrometer‐sized powders in aqueous solution . Zhang et al .…”