The photochemical machining of fine ceramics. Applicability of phosphoric acid as an etchant.
Year: 1989
Type: article
Abstract: The compositions of hot phosphoric acid between 200 and 320°C under refluxing and nonrefluxing (open) conditions were studied by means of the paper chromatography and the colorimetric analysis. The etch rates of various ceramics were measured in the acid under several conditions. The composition of the nonrefluxed open acid varied with time due to dehydration and condensation. On the other hand, refluxing water vapor during heating provided a good etching condition in which the temperature and composition of the acid were maintained constant. Under refluxing condition, two types of phosphoric acid were available ; a boiling acid and an equi-composition acid. In the refluxed acids, the etch rates of ceramics were increased with temperature. Alumina ceramic had an etch rate of several μm/min at temperatures above 250°C in the refluxed boiling acid. The etch rates for the equi-composition acid was lower than those for the boiling acid at the same temperature, due to a higher degree of condensation for the equi-composition acid. The etch rate of alumina ceramic was also increased with the concentration of orthophosphoric acid.
Authors: Eiji MAKINO, Yoshihiko YAMADA, Toshikazu SATO
Institution: Hokkaido University
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2324383796