Russian Journal of Nondestructive Testing

The article considers the ultrasonic method of non-destructive testing of samples, which are single crystals of molybdenum-niobium alloy, manufactured by the method of crucibleless electron-beam zone melting. The propagation of transverse elastic vibrations in an anisotropic single crystal is simulated. Based on the simulation results, the optimal testing parameters are selected. Experimental studies are carried out on samples with artificial surface defects in the form of scratches of different depths

The article deals with the problem of detecting potato tubers with phyto-diseases and mechanical damage in the early stages, which is critically important to prevent spoilage of the harvested crop during storage and transportation. The authors explore the method of active thermal control as a promising alternative to traditional methods (visual, multispectral, hyperspectral). The main idea of the method is to periodically heat the tuber surface with infrared radiation and then analyze not only the amplitude but also the phase of temperature fluctuations on the surface using a thermal imaging camera. Numerical modeling in the COMSOL environment and subsequent experiments on real samples have shown that the proposed method makes it possible to effectively detect both surface and subsurface defects (for example, dry rot) at a depth of up to 2 mm, while reducing the influence of contamination, glare and uneven illumination due to the curvature of the surface. It has been established that low periodic heating frequencies (less than 0.1 Hz) and a heat flux density of up to 1700 W/m² should be used for optimal detection of defects at various depths. The use of an artificial neural network to classify images based on amplitude and phase components has made it possible to achieve 88% error detection accuracy

The necessity of developing new methods for non-destructive testing of silicon targets structure and detection of internal defects in them is substantiated. It is established that a number of internal defects are not identified by the methods used for testing targets (these defects appear only during vidicon operation). For the targets, a study of the substrate structure and the formed topology, as well as the surface of the photosensitive elements, was carried out using X-ray diffractometry and a developed optical microscope with the formation of a diffraction image. Substrate deformation was established, which led to the formation of mechanical stresses with an increase in the concentration of charge carrier generation centers. A significant violation of the (111) orientation in the structure of the Si target substrate was detected. A new result was obtained that explains the formation of white illumination in the recorded images during vidicon testing and two reasons for the formation of an internal defect in the target, which led to its appearance, were established. Uneven impact along the edges of the target when pressing it on the indium ring and uneven application of layers during the manufacture of its structure. A new non-destructive method of testing silicon targets has been developed to detect this internal defect and others during their manufacture before installation in the vidicon. A number of measures have been proposed to eliminate these defects during the implementation of the technological process

Reference test blocks with 5 to 20 artificial defects each have been developed. The geometric characteristics of all defects are fully certified within the following ranges: opening width 0.5—5 µm, depth 40—640 µm, and length 1—17 mm. The blocks allow for microscope measurements of both the opening width and length of surface defects, as well as their depth, while simultaneously ensuring that defect cavities do not extend onto the block’s side surfaces. Comparative evaluations of the sensitivity classes of penetrants manufactured by Helling (U 88, Rot 3000), Magnaflux (Bycotest FP42) and Russian-made (PF-01, Klever and PS-42) have been performed. A series of comparative photos of penetrant testing results and experimental data on the dependence of defect indications areas on their geometric characteristics are presented