Key points of the A1 method
In 1.5~3.5N sulfuric acid solution, tetravalent titanium and hydrogen peroxide form a stable color complex, and the amount of titanium is determined by colorimetry.
A2 reagent
Ammonium nitrate (chemically pure) 10% aqueous solution;
b. Sulfuric acid (chemically pure): 1:9 (volume ratio) aqueous solution c. Sulfuric acid (chemically pure): specific gravity 1.84
d. Nitric acid (chemically pure): specific gravity 1.42;
e. Phosphoric acid (chemically pure): specific gravity 1.70;
f. Ethanol (chemically pure);
g. Hydrogen peroxide (chemically pure): 3% solution;
h. Titanium standard solution: containing 0.1 mg/mL of titanium.
A3 analysis program
A3.1 After cleaning the cadmium-plated titanium sample, put it in an oven at 120°C for 30 minutes, take it out, put it in a desiccator, cool it to room temperature, and weigh it. Place the sample in a 150mL beaker, add 20mL of 10% ammonium nitrate solution, and after the cadmium and titanium coating is dissolved, use a glass rod with a rubber tip to wash the attachments on the surface of the test piece in the beaker, take it out, rinse it with water, and wash it with ethanol. Dehydrate, then put it in an oven at 120°C for 30 minutes, take it out and put it in a desiccator to cool to room temperature and weigh. The difference between the two weights is the quality of the cadmium-titanium coating to be tested.
A3.2 Add 1~2mL of nitric acid and 5mL of sulfuric acid into the above-mentioned 150mL beaker, heat until white smoke comes out, dilute with water to the mark after cooling and stir well. Use a 2cm cuvette to perform colorimetry at a wavelength of 460µm, measure the extinction value, and check the corresponding titanium content on the titanium standard curve.
A3.3 Drawing of titanium standard curve: Take 0, 1, 2, 3, 4, 5mL of titanium standard solution respectively and put them into six 50mL volumetric flasks, add 20mL of 1:9 sulfuric acid solution, 1~2mL of phosphoric acid, 3% 2mL of hydrogen peroxide was used to develop color, and then, each 1:9 sulfuric acid solution was added to the scale and stirred evenly. Use a 2cm cuvette to measure the extinction value by colorimetry at a wavelength of 460µm, and draw a standard curve.
A4 calculation
