Study On Microwave Digestion Of Aluminum-zirconium Alloys And Polarographic Determination Of Zirconium

Zirconium is low-density, high hardness, corrosion resistant, etc, so it is used widely in electronics, aerospace, aviation, chemical, biological and medical fields. Aluminum-alloys can make the grains be refined while adding zirconium, zirconium not only can improve the thermal property, but also can reduce the crystallization temperature of aluminum-alloys, at last zirconium can increase strength of the alloy.The content of zirconium in aluminium-alloys has effect on the quality of their property and use, so it is very important to detect the content of zirconium. Because zirconium is corrosion resistant, the preparation before zirconium determination is the key problem. There are few methods to detect zirconium with wide detection range, so establish an accurate, convenient and quick, low cost detected method is very meaningful. This experiment just studied on the microwave digestion and determination of zirconium in Aluminum-alloys.First the conditions of determination of zirconium with EDTA titration were optimized. And a novel method of microwave-assisted digestion with HCl-H₂O₂ for the difficultly dissolved Aluminum-zirconium alloy was established. The microwave digestion conditions are optimized and the cost of the experiment is minimized. Then the proposed method was also compared with the traditional method. The titratal condition is that: at 100℃, adding xylenol orange as indicator, adding hydroxylamine hydrochloride as sequestering agent.Research results showed that the digestion process is heating 3min at 119W, 3min at 385W and 6min at 700W. There is no significant difference between the two methods on accuracy (RD is 0.7%,RSD is 0.3663% ) for zirconium. But the proposed method is novel, rapid, economic and convenient; it's valuable to be widely applied.A new method for determination of zirconium by polarography also has been established. The best determination conditions are as follows, 0.24mol/L of HCl - 8.0×10^-5mol/L of SAF–2.4mg/L Polyethylene Glycol(20000), an irreversible reduction peak of SAF has been found around of-0.68 V (vs. SCE) on mercury working electrode. After the addition of zirconium into complex solution, the reduction peak currents reduced. The peak is linearly proportional to the concentration of zirconium over the range of 0⁸.4×10^-1μg/mL, and the detection limit is 0.0042μg/mL. After the microwave-assisted digestion with HCl and HCl-H₂O₂, the recovery rates of samples is 99.45%。It was proved by single-sweep polarogrophy that the reaction of zirconium at the electrode had the characteristic of irreversible reductive adsorptive wave and the electro-active complex is salicyl fluoronl (SAF), a brief discussion of the electrode reaction was also given.