Jarosław Chmiel

Effect of Cavitation on Absorption and Transport of Hydrogen in Iron

Using the specially designed ultrasonic cavitation facility enabling to measure the hydrogen permeation, the experimental evidence have been provided for hydrogen to ingress in the metal subjected to cavitation in the 3% NaCl solution under the open circuit conditions. Increase in the vibration amplitude resulted in the increase in amplitude of the electrochemical voltage and current pulses and in the hydrogen permeation rate, as well. The cavitation induced modification of hydrogen transport through the membrane has been stated on the base of different appearance of the hydrogen permeation transients at cavitation in comparison with those recorded for the unstressed membrane. The hydrogen behavior has been affected by the cavitation induced dynamic stresses, metal hardening and stress relaxation due to microcracking of the metal.

The Role of Dust Fractions of Rapeseed Meal in the Wear of Cargo Handling System

The role of powdery fractions of rapeseed meal in the development of wear and destruction of cargo handling systems was showed. The physicochemical characteristic of rapeseed meal was studied. The results of research on the participation of powdery fractions in the wear of tribological nodes were presented. It has been found that the presence of the fraction containing the pieces of seed coat accelerates erosion processes. The smallest fractions < 75 μm stabilized the oil film and can reduce the intensity of wear of the friction. The role of powdery fractions in the initiation of dust – air mixtures explosion was presented.

Selected Issues of Corrosive - Mechanical Wear in the Port Grain Elevator

The article presents results of long years operational research of the real object localized in the maritime port. The aim of research was the identification of phenomena occurring between grain cargoes and handling equipment. The properties of grains and related products make, that in devices for internal transport systems take place the phenomena of intense erosive wear. The corrosive phenomena, typical for moist environment in the port; additionally speed up the destruction of the steel elements of internal transport system inside the grain silos. There has been discussed the main mechanisms of wear, indicating the fundamental role of the corrosive - mechanical processes. The results of studies of selected properties of grain products, affecting the intensity of the wear of materials of the handling facilities in the port grain elevator have been presented in the article, as well.

The Identification of Wear Processes in Production and Transport of Concrete Mixtures

The article presents issues concerning processes of wear of devices taking part in the production process in a concrete mixing plant and in the supplying of concrete to the construction place. Producers put the strength of concrete as the main indicator of quality. The processes of interaction of each component of concrete mixtures for operating the equipment are placed on a further location. This article pays attention to the processes that cause wear of individual components of equipment, which in turn can significantly affect the cost and quality of the concrete. The article presents studies results of the operation of a real object on the example of the concrete plant and concrete pump.

The Influence of Liquid Refrigerant on Refrigerating Compressors Sliding Surfaces

Reasons of compressors failures are connected with different operating conditions of individual parts. One of compressor damage reasons is pouring it over with liquid refrigerant. The purpose of this work was to carry out tests concerning the influence of refrigerant being in the liquid phase on piston compressor sliding surfaces. Tests were carried out in the mixture of synthetic polyester oil with liquid refrigerant R134a. The tests were performed with the use of the friction machine and the pair type block-on-ring simulating the refrigerating compressor inside and with the use of the real refrigerating compressor. The obtained results confirm the unfavourable influence of liquid refrigerant on friction elements in the refrigerating compressor. The role of hydrodynamic phenomena in the development of damage to the compressors has been showed.

Role of Hydrogen in Cavitation Degradation of Iron in Water Solutions

Hydrogen ingress into a metal has been observed at cavitation in distilled water and in 3% NaCl solution at open circuit potential. The measurements of hydrogen permeation rate have been made using an ultrasonic cavitation facility with an attached Devanathan-Stachurski double cell. Increase in vibration amplitude has been associated with the increase in amplitude of electrochemical voltage and current pulses and with the modification of hydrogen permeation rate. Hydrogen behavior within the metal has been affected by the cavitation induced dynamic stresses and metal deformation hardening, ascertained on the basis of the appearance of hydrogen permeation transients at cavitation in comparison with those recorded for the unstressed state. Metal damage has been a resultof associated effects of cavitation and hydrogen.

Influence of Spatial Structures of 316L Stainless Steel on its Cavitation Erosion Resistance

Cavitation erosion performance of modified macroscopic internal structure 316L stainless steel was investigated. The samples processed by means of SLM method were subjected to cavitation erosion test. The scanning electron microscope Philips 30/ESEM was used to examine morphology of eroded surface.

Stresses in the Surface Layer and Hydrogen Absorption and Diffusion in Cavitation Condition

Cavitation attack in liquids generated a various states of stresses in surface layers of metals. Differences in stress state effects on hydrogen absorption activated by the cavitation implosion. Results of XRD investigation and FEM modeling shows on inhomogenity of process.

Cavitation Erosion and Corrosion of Pearlitic Gray Cast Iron in Non-Standardized Cavitation Conditions

A results of test of erosion and corrosion resistance of pearlitic gray cast iron (grade EN GJ 400) are showed. The NaCl solutions and of ethylene glycol solutions were used as the test environment. Examination were performed at varying cavitation load, in the range 2,8 ÷ 20 W/cm2.

Correlation Between Pressure and the Amplitudes of Potential and Current in Electrochemical Oscillations Under the Conditions of Cavitation

The methods of adaptive medial filtration are used to select components of the initial electrochemical signal that can be identified as pressure pulses under the conditions of cavitation in the tests carried out in a vibration-testing machine. We determine the time dependences of the pressure pulses and selected electrochemical signals under the conditions of cavitation for a given potential.