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An apparatus for determining the wettability of quartz sand was developed. It was shown that as the temperature increases, the surface wettability of the minerals present in the glass quartz sand increases owing to a reduction of the slippage of the liquid along the solid surface and, in consequence, the aggregative stability of their suspensions increases.Aqueous disperse systems of hydrophylic minerals (quartz, iron and aluminum oxides, and others) are characterized by a high free interphase energy F, which always tends to decrease, which is the reason for aggregation of particles accompanied by a reduction of this energy (F ® min). As particles undergo aggregation the primary structural-mechanical properties of disperse systems change (the systems lose flowability and easy mobility, their viscosity increases, and the modulus of elasticity and ultimate strength come into play), which degrades quality in the production of modern building articles [1]. The factors determining the properties of a disperse system upon loss of aggregative stability are the force and energy of bonding (interaction) between particles in contact and the number of particles per unit volume.A special apparatus was developed to investigate the aggregative stability of disperse systems by means of sedimentation-volumetry (Fig. 1). In this setup the sediment forms on a porous barrier upon kinetic breakdown of the suspension with volumetric rate v and filtration outflow of the disperse medium.The apparatus looks like an hourglass, the only difference being that the reservoirs 1 and 2 are filled with water and connected by a long graduated tube 3 with a small diameter instead of a short tube. The analogy with an hourglass can be extended: when measuring time an hourglass is in- Fig. 1. Apparatus for sedimentation volumetric measurements: 1, 2 ) accumulating reservoirs; 3 ) small-diameter tube; 4 ) porous glass plate; 5 ) stopcock; 6 ) thermostating jacket; 7 ) stopper; 8 ) measuring scale; 9 ) water feed from thermostat.

A new series 6xxx Al-Mg-Si alloy is developed with grade V-1381. The influence of the composition and modes of heat treatment on the mechanical and corrosion properties of sheets with a thickness of 1 and 3 mm manufactured at the All-Russian Scientific Research Institute of Aviation Materials (VIAM) is investigated. The average properties of the sheets are as follows: the ultimate tensile strength is σ B = 410 MPa, the yield strength is σ 0.2 = 360 MPa, the elongation is δ = 11.5%, the fatigue crack growth rate is (dl/dN) = 0.59 mm/kcycle at ΔK = 18.6 MPa m 1/2 , the intergranular corrosion is IGC ≤ 0.15 mm, and the exfoliation corrosion (EXFC) is 4 points. It is found out that the sheets are structurally recrystallized, the main strengthening phase is the matrix-coherent β'(Mg 2 Si) phase evenly distributed with a high density across the volume of grains. Another observed process is the heterogeneous origin of the β′ phase on dislocations and dispersoids. The dispersoids observed in the tested specimens have various morphologies. The grain boundaries have emission-free zones 15-20 nm in width. The temperatures and heat values of phase transformations in ingots and sheets are determined, including the measurement of liquidus and solidus points. The sheet weldability is evaluated by automatic argon-arc welding, and critical strain rate V cr of the weld metal during crystallization is determined at which this metal is not covered with cracks. A laser welding mode has been developed to ensure optimal formation of the geometric parameters of the weld.

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