how to guarantee aluminium paste quality
gas aluminium paste it is made by aluminium foil with solvent is water to grinding to aluminium paste .
this type aluminium paste strictly follow China standard JCT407
the solid from 60-70% the gas normally finished within 16 minutes .
normally we are test aluminium paste solid , aluminium paste particle size , aluminium paste gas rate . and active aluminium test this four index can be decided aluminium paste quality .
DETERMINATION OF ACTIVE ALUMINUM
Determination of active aluminum in aluminum powder or paste should be made in a thick-walled metal Cup with a hermetically sealed lid (Fig. 1). In a metal glass with a volume of 1000 ml, pour 250 ml of a pre-prepared 10 % solution of caustic sodium or potassium at a temperature of 20 ± 0.5 ° C. Then take a sample of paste or dry aluminum powder 1 g and in a plastic Cup drop it into the glass on the surface of the alkali solution.
After that, the vessel is hermetically closed with a lid, and if the pressure gauge arrows have shifted from zero, then open the gas tap and equalize the pressure in the vessel with atmospheric pressure, and the glass is turned over so that the Cup overturns and sinks in the solution. Then the tap is closed again. At this point, the reaction of the alkaline solution with aluminum and the release of hydrogen begins. The pressure increases in the vessel, the value and speed of which is shown by the pressure gauge. The duration of the reaction does not exceed 5-7 minutes, which is detected by stopping the movement of the pressure gauge needle. If, at the end of the reaction, the arrow continuously moves to zero, this indicates a leak in the lid, and the determination should be repeated.
The reading of the pressure gauge at the steady position of the arrow is taken into account. The content of active aluminum, a,%, by weight of the paste sample or aluminum powder, is determined by the formula
where N is the pressure gauge reading;
V в- the volume of air space in the device above the alkaline solution, cm3 (V в = V п – V щ );
V п- volume of the empty glass in the closed state, cm3; 这个是空玻璃瓶关紧后的体积
V щ- volume of the alkaline solution poured into the device, cm3 (ml);这个是碱性溶剂体积
P – sample weight, g; 重量
Kt-coefficient for deviations of the solution temperature from 20 ° C溶液浓度偏差的系数。
Where t is the temperature of the alkaline solution after the experiment, deg;
1330 – volume of gas, cm3, released during the complete reaction of 1 g of active aluminum at a temperature of 20 ° C and at normal atmospheric pressure;