Reconstruction of Regression Relationships for Determination of Strength Values for Alloys of Products in Diffusion Welding

The article deals with the problem of obtaining the dependence of the product strength parameter on the welding time, welding temperature and pressure during mechanical tests, leak tests. The relevance of this work is due to the complexity of carrying out field experiments to identify dependencies. In particular, the complexity arises from the duration of diffusion welding and the high cost. Application of the method of regression analysis based on a non-compositional plan of the second order for three factors will allow to restore the dependence of the product strength parameter on the time during which welding was carried out, the temperature at which diffusion welding was carried out or could be carried out and on the applied pressure at which mechanical tests were carried out. In the current study, a non-compositional design of the second order for three factors was used - allowing to restore the dependence of the missing values of the strength of the product. The aim of the research is to improve the quality of mathematical modeling. Application of the proposed approach will make it possible to obtain the strength distribution function depending on time, temperature and pressure using the example of a product made of VT14 titanium alloy and 12X18H10T stainless steel. This will make it possible to obtain optimal parameters for the diffusion welding mode and to improve the quality of the resulting products.

Influence of Pressing Temperature on Wood Properties

Obtaining wood with high performance properties on the basis of chemical and mechanical action as a result of optimization of technological processes and the use of temperature exposure. The initial raw material is hardwood (aspen, alder), which are little used in construction and in the production of finishing materials. The condition for obtaining wood with high operating properties (increasing density, strength, reducing water saturation, ensuring the dimensional stability of samples for a long time) is the ability of wood as a natural polymer to change properties under the combined effect of temperature and pressure.

O2 Physisorption in Coal Pore: Effects of Pore Size, Pressure, Temperature and Function Group

In this paper, the physical adsorption characteristics of oxygen in coal pores were systematically investigated by the Grand Canonical Monte Carlo and the COMPASS force field. Firstly, coal pore structures of different sizes were constructed by graphite slit models and different groups. Secondly, the physisorption behavior of oxygen in graphite slit models of different sizes was simulated. Finally, the physisorption behavior of oxygen in graphite slit models at different pressures and temperatures was analyzed. The results showed that the physisorption density and excess physical adsorption of oxygen were divided into the rapidly decreasing stage (0.4-0.7 nm), the slowly decreasing stage (0.7-1.4 nm), and the stable stage (1.4 nm-5 nm) with the increase of coal pores, and the excess oxygen physisorption amount was more sensitive to the change of pressure. The O2 isosteric heat of physisorption decreased with increasing pore size of coal. Oxygen is more strongly adsorbed by hydroxyl and ether bonds than by methyl, carboxyl and carbonyl groups. Through this study, the mechanism of oxygen physical adsorption in coal pores and the characteristics influenced by temperature and pressure can be better understood.