A coating for equipment transported at minus temperatures

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 3, pp. 33, March, 1988.     

A study of the mechanoelectrical effect in strained electrically conducting solids

The relation between mechanical and electromagnetic phenomena in deformed electrically conducting non-ferromagnetic solids was studied. Basic equations were derived for the charge, electric field intensity, and electric potential of a solid acted on by external forces. For the case of plane deformation the problem was reduced to a corresponding boundary problem for the functions of the electric field potential and intensity, ponderomotive forces being taken into account in the derivation of appropriate equations. A detailed analysis was carried out of the case of an infinite body with a cylindrical cavity under tensile loads.     

Effect of stress concentration on the charge and electric field distribution in electrically conducting solids

A plane problem of electroelasticity of electrically conducting solids is reduced to a boundary problem of a complex variable function. The charge and electric field distribution in a circular zone under the influence of a normal load and in a plate with an elliptical hole under tensile loads applied at infinity is analyzed.     

Synthesis of active carbon-based catalysts by chemical vapor infiltration for nitrogen oxide conversion

Direct reduction of nitrogen oxides is still a challenge. Strong efforts have been made in developing noble and transition metal catalysts on microporous support materials such as active carbons or zeolites. However, the required activation energy and low conversion rates still limit its breakthrough. Furthermore, infiltration of such microporous matrix materials is commonly performed by wet chemistry routes. Deep infiltration and homogeneous precursor distribution are often challenging due to precursor viscosity or electrostatic shielding and may be inhibited by pore clogging. Gas phase infiltration, as an alternative, can resolve viscosity issues and may contribute to homogeneous infiltration of precursors. In the present work new catalysts based on active carbon substrates were synthesized via chemical vapor infiltration. Iron oxide nano clusters were deposited in the microporous matrix material. Detailed investigation of produced catalysts included nitrogen oxide adsorption, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Catalytic activity was studied in a recycle flow reactor by time-resolved mass spectrometry at a temperature of 423 K. The infiltrated active carbons showed very homogeneous deposition of iron oxide nano clusters in the range of below 12 to 19 nm, depending on the amount of infiltrated precursor. The specific surface area was not excessively reduced, nor was the pore size distribution changed compared to the original substrate. Catalytic nitrogen oxides conversion was detected at temperatures as low as 423 K.     

Dynamic characterization of multi-axis dynamometers

In this paper, we present a comprehensive technique for accurate determination of three-dimensional (3D) dynamic force measurement characteristics of multi-axis dynamometers within a broad range of frequencies. Many research and development efforts in machining science and technology rely upon being able to make precise measurements of machining forces. In micromachining and high-speed machining, cutting forces include components at frequencies significantly higher than the bandwidth of force dynamometers. Further, the machining forces are three-dimensional in nature. This paper presents a new experimental technique to determine the three-dimensional force-measurement characteristics of multi-axis dynamometers. A custom-designed artifact is used to facilitate applying impulsive forces to the dynamometer at different positions in three dimensions. Repeatable and high-quality impulse excitations are provided from a novel impact excitation system with a bandwidth above 25 kHz. The force measurement characteristics are presented within 25 kHz bandwidth using 3 × 3 force-to-force frequency response functions (F2F-FRFs), which capture both direct and dynamic cross-talk components to enable fully three-dimensional characterization. The presented approach is used to characterize the dynamic behavior of a three-axis miniature dynamometer. The effects of force-application position, artifact geometry, and dynamometer-fixturing conditions are explored. Moreover, the relationship between the force-measurement characteristics and structural dynamics of the dynamometer assembly is analyzed. It is concluded that the presented technique is effective in determining the force-measurement characteristics of multi-axis dynamometers. The changes in dynamometer assembly that affect its structural dynamics, including artifact (workpiece) geometry and especially the fixturing conditions, were seen to have a significant effect on force-measurement characteristics. Furthermore, the force-measurement characteristics were seen to change substantially with the force-application position. The presented technique provides a foundation for future compensation efforts to enable measuring forces within a broad range of frequencies.     

Effect of groove-type chip breakers on twist drill performance

This paper proposes the use of grooves placed on the rake face of a twist drill to facilitate chip breaking and reduce drilling forces and chip clogging. A procedure to design grooves including groove geometry and orientation is discussed. Two sets of experiments are presented that determine the effect of grooves on the forces, chip morphology, and critical depth, and compare the life of the grooved and ungrooved drills. The grooves are found to be very effective in breaking chips and preventing chip clogging. Experiments show the positive effects of the grooves including lower drilling torque and thrust, lower chip evacuation forces, lower cutting forces, increased critical depth and increased drill life.