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Transparent conducting oxides CdIn2O4 thin films were prepared by direct-current (DC) reactive magnetron sputtering from a Cd–In alloy target in Ar+O2 atmosphere. The thickness of the films prepared in different oxygen concentration, substrate temperature and annealing treatment was calculated by an envelope method from transmission spectra. Meanwhile, the optical constants and the optical band gap of these films have been determined. It is found that the thickness of the films increases with the decrease of oxygen concentration or substrate temperature, and the optical band gap increases with the decrease of oxygen concentration or the increase of substrate temperature. After annealing treatment, the thickness decreases sharply and the band gap widens. The optical properties are sensitive to the preparing conditions and annealing treatment, which is due to the “Burstein–Moss” shift and many-body effect. The width of localized states E0 is determined and the effect of band tailing is substantial.

Nanoparticle magnesium borate with a particle size of about 10 nm was prepared using ethanol supercritical fluid drying technique and was characterized with TEM, XRD and X-ray small angle scattering. Tribological properties of the nanoparticle magnesium borate, using as lubricating oil additive, were evaluated using a four-ball and a block-on-ring tribotester. The wear scar was characterized with SEM and XPS. Results indicate that the wear resistance and load carrying capacity of the 500 SN base oil were improved and the friction coefficient of the oil was decreased by the additive. FeB were formed on sliding surface.

A supercritical carbon dioxide drying technique was developed to prepare nanometer particulate materials. The technique consists of preparation of an aqueous gel, filtering, washing, replacement of the water in the gel with a mixture solvent of n-butanol and ligroin and supercritical carbon dioxide drying. The product was characterized with TEM, XRD and X-ray small-angle scattering. The results indicated that an amorphous aerogel of the beryllium borate was obtained with this technique. The diameter of the product particles was about 7 nm. Isopropyl alcohol supercritical drying was also used to prepare aerogel beryllium borate, where recrystallization took place due to the high critical temperature of isopropanol.

Nanoparticle amorphous lanthanum borate with a particle size of 20–40 nm was prepared with a Replacing Solvent Dry technique and characterized using TEM and XRD. Its tribological properties as a wear resistance additive of lubricating oil were evaluated with a four-ball tribotester. The wear scar was characterized with XPS. The wear resistance and load carrying capacity of 500 SN base oil was improved by the lanthanum borate. Diboron trioxide and FeB were formed on the wear scar surface. These tribochemical reaction products as well as some depositions formed a wear resistance film on the rubbing surface, which provided the oil with an excellent load carrying capacity.

n-Butanol supercritical drying technique was developed to prepare nanometer particles. The procedure mainly consisted of sol preparation, filtering as well as washing, replacement of water in the precipitate with n-butanol and supercritical drying. Anatase and rutile mixture with a particle size of 10–20 nm, a surface area of 166.8 m2/g and a pore volume of 1.286 ml/g was obtained using the preparation technique. No marked coagulation was caused by the effect of water–n-butanol interface tension in the thermal treatment to replace water in the precipitate with n-butanol. Ethanol supercritical drying also gave anatase titanium oxide. The thermal treatment during the preparation of both ethanol and n-butanol supercritical drying resulted in evident growth of crystal.

A supercritical carbon dioxide drying technique was developed to prepare nanometer particle. The process of the technique mainly consisted of a preparation of gel in aqueous solution, filtering, replacement of the water in the precipitate with a mixture of n-propanol and benzene, supercritical drying. The technique can be industrialized easily and can be widespreadly used in the preparation of nanometer metal hydroxide, salt that are insoluble in water and propanol. Copper borate with a particle size of 10–20 nm, a surface area of 247.7 m2/g and a pore volume of 1.059 ml/g, was prepared using the method. The surface area and the pore volume were much larger than that of the sample prepared using precipitation method.

Amorphous ferric oxide with a particle size of about 20–50 nm was prepared using the ethanol supercritical fluid drying technique. The tribological properties of 500 SN oil containing nanometer particles were measured using four-ball and block-on-ring tribotesters. Results indicated that the wear resistance and load-carrying capacity of the oil was raised and its friction coefficient was decreased. Excessive nanometer additive was disadvantageous for the load-carrying capacity of lubricating oil. The dispersing agent played an important role in the improvement of the tribological properties, and copper stearate was markedly superior to sorbitol monostearate. Nanometer ferric oxide took effect by its deposition on the rubbing surface.

Nanometer crystal titanium oxide with a particle size of about 20 nm was prepared using ethanol supercritical fluid drying technique. Tribology properties of 500 SN oil with the nanometer particles were measured using four-ball and block-on-ring tribotester. Results indicated that wear resistance and load carrying capacity of 500 SN base oil were improved and friction coefficient was decreased by an addition of the nanometer particles. There was an optimal content of titanium oxide in the oil, which gave the highest maximum nonseized load. Nanometer titanium oxide took effect by its deposition on rubbing surface.