Influence Of Aging Process Research Articles

The Influence of Aging Process on Microstructures and Properties of an Al-2.54Li-1.61Cu-1.23Mg-0.22Zr Alloy

The influence of aging process on microstructures and mechanical properties of a rapid solidification Aluminum-Lithium alloy has been analyzed in this paper. The results show that the better aging process is as follows: heating to 170oC for 4 hours and then followed by a final aging at about 190 oC for 18 hours. A lot of fine participated second phase such as δ′ in matrix and a narrow participation free band make alloy’s good performance.

Study on ageing and creep of Al–0.1Zr alloy

The influence of ageing process on speed of the creep crack growth of aluminum alloy containing 0.1% zirconium has been studied. By TEM and EPMA, the effect of ageing precipitates’ size and distribution on the creep crack growth of the alloy has been also analysed. The results show that many Al 3Zr particles can be precipitated out from the matrix after aged at 250 °C for 48 h. The particles are fine and dispersive, and lay in grain or on grain boundary. These particles can prevent the creep crack growth effectively. In this case, a small amount of zirconium exhibits stronger ability to resist creep crack growth. After aged at 200 °C for 48 h or aged at 250 °C for 24 h, the precipitated particles are invisible and cannot restrain the creep crack forming and growth effectively. After aged at 300 °C for 48 h, the alloy is overaged. The peak of age hardening curve corresponds to the ageing process of 250 °C × 48 h after a 530 °C × 1.5 h solution treatment.

Influence of ageing process on porosity changes of the external plasters

In recent time more and more attention has been paid to the durability problems of building materials and components. The key issue in this area is to define the service life. Therefore, useful methods for durability valuation are of prime importance. In the paper we present a method to define an acceleration ageing coefficient involving naturally and simulate degradation of external mineral plasters. To reach the above objective, elements of the kinetics process theory used in chemistry and power engineering have been adopted for the description of changes in pore-capillary materials. The emphasis has been placed on open capillary porosity, which was examined over time by mercury porosimetry method. Plasters were exposed to ageing processes in the natural and an artificial environments. Basing on that, the porosity changes in plasters in both environments and their mutual relation were studied. An acceleration coefficient of ageing process has been established, which can be used for durability assessment on the grounds of a short laboratory test.

Influence of aging process on biochemical changes in sunflower seed

This investigation was conducted in order to determine the degree of biochemical changes during accelerated and natural aging of sunflower seed. Five sunflower lines developed in Novi Sad, submitted to accelerated aging for three and five days, and natural aging of six and twelve months under conventional storage and controlled conditions, were used in these trials. Malondialdehyde, superoxide dismutase contents and peroxidase activities were studied. Lipid peroxidation and superoxide dismutase and peroxidase activities (especially pronounced in accelerated aging variant) were caused by both types of aging. The degree of seed damage and the ability of seed to resist the negative consequences of aging were influenced, beside duration of aging period, by type of storage and characteristics of sunflower lines.

The influence of ageing process on switching kinetics in (Ch3NH3)5Bi2Br11 crystals

The influence of ageing process on switching kinetics has been investigated in (CH3NH5)5Bi2Br11 crystals by using the nematic liquid crystal method. Microscopic observation established that degradation of switching characteristics during ageing process is the consequence of domain structure stabilization which has revealed experimentally as the gradual reduction of number of nucleated domains in electric field.

Influence of Aging Processes on Adhesion Properties of Metallic and Oxidic Thin Films

AbstractAdhesion of oxidic and metallic films with thicknesses between 40 nm and 350 nm has been investigated by means of a scratch-test method based on a vibrating diamond micro-indenter. SiO2 and TiO2 films are precipitated on fused silica substrates by sol-gel techniques (SG), reactive evaporation (RE), reactive low-voltage ion plating (IP), and plasma impulse chemical vapour deposition (PICVD), and Cr-layers are produced by rf magnetron sputtering (SP). The influence of aging effects on film adhesion is investigated in respect of several conditions, like storage under ambient surroundings with differences in relative humidity or temperature treatment. A method is presented allowing control of the long-term stability of the scratch-test conditions. Temperature treatment up to 600 °C is found to have the most significant impact on adhesion properties. Adhesion increases for some SiO2 films, whereas for TiO2 layers an opposite behavior is observed. Here, the adhesion of the originally amorphous titania films is reduced due to the phase transition to polycrystalline anatase, which correlates with a significant increase in film stress.

Oxygen evolution reaction on electrochemically generated thick cobalt oxide films

The electrocatalytic characteristics for the oxygen evolution reaction in alkaline solutions of cobalt oxide films obtained by periodic potential treatments were studied. The influence of ageing processes and thermal treatments on the reaction kinetics were evaluated. In addition, the real exchange current was determined through the analysis of the dependence of the apparent electrocatalytic activity on the oxide charge.