Application of nanotechnologies in aerospace industry

FSUE Obninsk Research & Production Corp. Technology has conducted research in nanotechnology for more than 15 years; to date it scores some serious practical results introduced to particular products of aviation, aerospace and other application domains thus significantly enhancing their performance. Research is implemented in several directions.

The first direction aims at development of thin-film coatings for engineering and instrumental optics.

A physical mechanism behind adjustment of product optical properties through surface modification lies in interference of electromagnetic waves. In most cases, thickness of optical filter coating is a value divisible by ¼ of emission wavelength which we would like to reduce. For the visible band emission it would be 10-125 nm. By varying the number of layers with different refraction indices and their thicknesses, it will be possible to create various types of optical light filters.

The company project team developed an industry process to apply multifunctional 3-10 nm coatings over silicate and organic glass transparency products by cathodic magnetron deposition. This technique provides for 3-4-fold reduction in electromagnetic radiation over crew and cockpit instruments, mitigation of solar thermal flux by 40 % in the 0.9-2.5 μm wave band, enhances optical and antiglare properties due to decrease in reflection factor for glass surface in 400-740 nm visible band, considerably improves abrasion resistance, silver- and moisture-resistance, thermal stability of optical and strength properties of glazing. Glaze products with developed coatings are delivered to new aircraft such as MiG-29К, Su-30MKI, Su-35, to Ansat and Ka-62 helicopters. Possibilities of nanocoatings will grow to match developing processes of creating ever thinner layers to cover a wider range of materials.

Fig. 1. Chamber for deposition of nanocoatings

First successful trials are already completed to obtain packings with applied nanocoatings whose properties allow to suppress a wide range of bacteria.

The company staff developed a certain research stake in theory and now prepares experimental capabilities to create precision plasma coatings for unique femtosecond laser systems. It is planned to obtain multilayer coatings (up to 100-150 layers), with some layers being several nm thick, so as to develop chirped mirrors (multilayer coatings).

The second direction is represented by development of electrochemical devices which use zirconium oxide-base solid electrolytes. Solid-state electrolytes stand for ZrO2 solid solution with addition of yttrium, calcium, magnesium, aluminium and other metal oxides which feature ion conductance through oxygen. The unique combination of high thermo-mechanical and conductive properties based on partially stabilized ZrO2 is responsible for their wide use as solid electrolytes for high-temperature electrochemical devices in various applications:

— in oxygen control sensors inside cockpits;
— in high-temperature water electrolysers for hydrogen generation;
— in fuel cells;
— in oxygen pumps;
— in oxygen control sensors to optimize casting of high-quality structural steel, to minimize exhausts of noxious agents in car engines and to optimize and control processes in chemical and nuclear power installations.

Nanocrystalline zirconium dioxide powders are used as source materials for solid electrolytes.

Fig. 2. Structure of zirconium oxide powders made by FSUE Obninsk Research & Production Corp. Technology

When using nanocrystalline powders (with 35-40 nm crystalline particle), Technology specialists created unique structures with particle sizes of 100-150 nm which enable enhanced thermal stability and crack-resistance, extended range of operating temperatures and pressures in high-temperature electrochemical devices.

The third direction in research concentrates on studies aimed at enhancing strength-elasticity behaviour in carbon composites based on the nanoparticle-modified epoxy matrix. Sol-gel processing was used to introduce zirconium oxide nanoparticles and other nanomodifiers into the epoxy matrix. Modification of polymeric matrix with zirconium oxide nanoparticles allowed specialists from Company and other Russian institutes to increase strength-elasticity properties of polymeric composite material by 25-30 %. High consistency of obtained results is observed (variation between minimal and maximal values of ultimate compressive strength for nanomodified carbon composite is two times low if compared against the nonmodified composite).

Fig. 3

Fig. 4

Composite material parts manufactured by this process make it possible to produce lightweight products with enhanced strength properties: craft bodies and accessory parts.

The fourth direction in work concentrates on development of materials with thermal conductivity lower than air conductivity.

To achieve such heat insulating properties, Technology scientists picked up fine nanostructure materials. Since thermal conductivity depends not only on the overall porosity of material but on pore sizes as well, nanostructural heat insulation materials with pores below 100 nm have conductivity close or even below that of air conductivity. It is because in this case the pore diameter is less than an average free path of gas molecule, whereby gas molecules would run into pore walls only, without transfer of energy through elastic impact, thus making it possible to reduce thermal conductivity down to extra-low values.

Thermophysical evaluation of trial samples corroborated correctness in selection of composition and production process for the new TIM-MP heat insulation material. As seen from Fig. 5, heat conductivity factor of nanostructural heat insulation material is significantly lower compared to fibre materials of TZMK type.

Fig. 5. Temperature dependence for thermal conductivity factors of fibre / nanostructural heat insulation materials

Major trends in application of TIM-MP material lie in arranging heat insulation of:

— airborne flight data recorders on aircraft and helicopters to preserve their operational capacity in emergency;
— engines in commercial aviation, rocket and missile engineering;
— pouring ladles and other accessories designed for metal / alloy casting ;
— power-generating equipment, industrial furnaces.

Source: Federal Internet portal Nanotechnologies and Nanomaterials,www.portalnano.ru