ISO 21822 pdf download Fine ceramics (advanced ceramics, advanced technical ceramics) — Measurement of iso-electric point of ceramic powder
Materials that do not elute in the range of pH 2 to pH 10 should be used.Special care is needed for sodalime glass, which may elute in a strong base condition.
The sample should be dispersed by a tip sonicator, preferably, or a bath-type sonicator. A homogenizer,mortar, or vacuum degassing machine can be applied when needed.
A balance with a measuring capacity of 200 g or above with 10-mg precision.
A thermometer with a measuring range of 0 °Cto 50 °C with a precision of 0,5 °C.A built-in temperaturesensor is also applicable.
A stirrer or magnetic stirrer coated with polytetrafluoroethylene resin.
This shall be ion-exchanged distilled water with a conductivity of less than 1 × 10-+S/m (25 °C) in anelectrolyte solution.
6.2pH-adjusting acid or base and electrolyte solution
The pH-adjusting acids or bases and the type of electrolyte solution shall be selected as follows.
a)The pH-adjusting acid and base shall be hydrochloric acid (HCl) or nitric acid (HNO:J and sodium
hydroxide (NaOH) or ammonium hydroxide(NH,0H), respectively. The electrolyte solution shallbe a salt, sodium chloride (NaCl) or ammonium nitrate(NH,No-) solution with a concentration of0,1 mol/l for acid and base and 1 mmol/l to 10 mmol/l for the electrolyte solution.
b) Any combination of inorganic acid and base with an oxidation number 1, except those in a), may be
selected, and their electrolyte (1 mmol/l to 10 mmol/l) may be selected.
6.3Sample preparation and dispersion
The dispersion solution of ion-exchanged distilled water shall be selected as in 6.1 and an electrolytesolution of 10-3-10-2 mol/l prepared.The powder sample shall be dispersed in the electrolyte solutionto produce a ceramic slurry of suspension.
The ceramic slurry shall be well dispersed by using a tip sonicator or ultrasonic bath. The ultrasonicirradiation shall be carried out as follows. If the ultrasonic bath is applied, place the sample abovethe spot of oscillation for no less than 3 min below 300 w power. If using an ultrasonic tip sonicator,place the sonicator tip in the middle of the beaker bottom and top liquid interface of the ceramic slurry,sonicate for 1 min to 5 min and stabilize for 5 min to prevent any temperature increase.