Zirconium dioxide. Review

A review of zirconium dioxide or zirconia ZrO2 is presented. The finding of zirconium compounds in nature, the physical and chemical properties of ZrO2 are given, the polymorphism of zirconium oxide, and the phase diagrams of systems with its participation are considered. The areas of application of zirconia compounds are highlighted: automotive industry, electronics industry, energy and industrial ecology, equipment manufacturing and mechanical engineering the production of zirconium-based refractories, ceramics, enamels, glass, superhard materials, applications in medicine, nuclear energetics, and many others areas of human activity. Cubic modification of zirconium dioxide, stabilized by oxides of rare earth elements,is a jewelry stone (fianite). Partially stabilized zirconium dioxide is a versatile structural material with very high resistance to crack propagation. Solid solutions of REE oxides, especially scandium, have a high oxygen conductivity, which is used in sensors for measuring the partial pressure of oxygen and in fuel cells. Attention is paid to heat-resistant oxide ceramic materials with low thermal conductivity used in the quality of heat-resistant coatings. Considerable attention was paid to the second most important mineral of zirconia - baddeleyite (ZrO2). Baddeleyite is widely used in the production of refractory materials. It is mined for the production of metallic zirconium. The achievements of Soviet and Russian scientists in thedevelopment of technologies for the production of fianite and artificial baddeleyite are presented.

Synthesis and Characterization of Zirconium Nitride Nanopowders by Internal Gelation and Carbothermic Nitridation

Zirconium compounds has been widely attention over the last decades due to its excellent physical and chemical properties. Zirconium nitride nanopowders were synthesized via a simple direct carbothermic nitridation process of internal gel derived zirconia in the presence of nano-sized carbon black. The effects of reaction temperature, dwell time and molar ratio of carbon black to Zr (C/Zr) on the phase composition, grain size and crystal parameters of products were studied. Based upon the analysis of crystallite phase evolution and microstructure characterization, it was found that zirconium oxynitride is intermediate product and then O atoms in oxynitride were extracted by oxygen getter, carbon black. Anion sites were directly replaced by N atoms to form rock-salt type nitride in carbothermic nitridation process.

Zirconium in modern analytical chemistry

Detailed monographs on the analytical chemistry of zirconium, which is widely used in all fields of modern science and technology, were published in the 1960s–1970s of the last century. This review summarizes information on the modern methods for determination of zirconium in a great variety of natural, technical, and biological objects. Focus is made on the works published in scientific periodicals after 2005. Spectroscopic techniques of zirconium determination including molecular and atomic spectrometry, X-ray fluorescence analysis, and electrochemical and activation methods are described. The paper also describes the applications of zirconium compounds, in particular, in analytical chemistry.

Catalytic N–Si coupling as a vehicle for silane dehydrocoupling via α-silylene elimination

Zirconium compounds appear to promote the liberation of silylene fragments via an N–Si coupling event.

DESIGN OF THE REGENERATION METHOD OF HYDROXYL-CONTAINING ZIRCONIUM COMPOUNDS IN PROCESSES OF WATER PURIFICATION FROM BORON

The regeneration method of zirconium hydroxide sorbent spent in the boron sorption process by diluted solution of acids as well as the principle recycling diagram of the formed regenerating solution by the nanofiltration process with the OPMN-P membrane were proposedin this work. The permeate obtained can be used as a boron-containing microfertilizer (ammonium salt + boron) after it has been neutralised with ammonium hydroxide. Zirconium-containing concentrate may be reused for sorbent preparation. The effectiveness of separation of the regenerating solution components by nanofiltration is demonstrated by high values of zirconium rejection coefficient in this process (RZr ~98– 99%) and low values of boron rejection coefficient (RB ~12%). In this case the specific performance of the membrane is about 50 dm3/m2·h.

The formation process of Zr-doped silane film on carbon steel during immersing in Zr(NO3)4/silane mixed solutions

Purpose Immersion is one of the key steps during the preparation of silane-based hybrid films, which has important effects on the performance of films after curing. In this paper, the formation process of Zr-doped silane film (i.e. the adsorption of silane and deposition of zirconium compounds) on carbon steel immersed in Zr(NO3)4/silane mixed solutions was investigated. Design/methodology/approach The method of in situ monitoring the open circuit potential of a two-electrode system, consisting of carbon steel and saturated calomel electrode, was used. The effects of immersion conditions (i.e. the concentration of Zr(NO3)4 and pH of Zr(NO3)4/silane mixed solution) on the open circuit potential were investigated in detail. Furthermore, the surface coverage rate of different cured films (i.e. Zr cured film, silane cured film and Zr/silane composite cured film) after curing on carbon steel was calculated according to the results of polarization curves. Electrochemical impedance spectroscopy (EIS) was used to study the self-healing property of Zr-doped silane cured film. Findings The results indicate that in Zr(NO3)4/silane mixed solutions, most zirconium compounds deposit on the surface of carbon steel at the initial immersing stage, then the adsorption of silane on the residual surface of carbon steel dominates the following immersing stage. EIS results show that the Zr-doped cured film has improved self-healing property. Originality/value First, the method of in situ monitoring the open-circuit potential of two-electrode system was applied to investigate the deposition of Zr and the adsorption of silane on carbon steel immersed in Zr(NO3)4/silane mixed solutions. Second, the formation process of Zr-doped silane film was proposed.