Dariusz Golański

Investigation of ceramic-to-metal joint properties by hybrid moire interferometry/FEM analysis

Due to the significant difference in the physical and chemical properties of ceramics and metals, the joining process of these materials provides several problems. The paper describes a hybrid experimental-numerical approach for determination of stresses in C-M joint. Automated moire (grating) interferometry is used as a full-field experimental method providing in-plane displacement/strain data, as well as the local values of Young modulus at the vicinity of the C-M joint. These data can be used as the input for the finite element analysis for full stress state determination in the joint. Analysis of Al2O3-FeNi42 specimens manufactured with different temperature and time of brazing was employed to determine optical technological parameters of the joining process.

Temperature distribution in a cylindrical Al2O3-steel joint during the vacuum brazing cycle

Abstract This paper deals with the investigations of temperature distribution during vacuum brazing of cylindric Al 2 O 3 and steel samples, using the AgCuInTi active filler metal. The thermovision system AGA 680S was used to register the temperature field during brazing cycle. Bonded joints were observed by the infrared scanner unit during heating, brazing and cooling. Two types of joints with different shape of steel element were examined during temperature measurements. Additionally, a 2D finite element code “ADINA-T” was used to solve for the problem of nonlinear transient thermal analysis of temperature distribution in the axisymmetric models of Al 2 O 3 -steel brazed joints. The experimental results revealed the presence of big transient axial temperature drops in the ceramic part. The change of metal shape resulted in a reduction of the transient temperature drops in the ceramic element. The finite element calculations corresponded well with the results of measurements and showed that the perfect thermal contact between adjacent surfaces plays the important role in heat transfer and can be a factor affecting temperature gradients in ceramic.

Selected properties of Ti coatings deposited on ceramic AlN substrates by thermal spraying

This paper presents the results of an investigation of selected properties of Ti coatings deposited onto ceramic AlN substrates obtained by the detonation spraying method. It discusses and illustrates the microstructure of the coatings and joints among Ti coatings and AlN substrates. The results of linear distribution of Ti and Al in the cross section of the joint are also included, together with the stereometric patterns of the surface structure of Ti coatings deposited on AlN ceramic substrates. Finally, an finite element method modelling analysis of thermal residual stresses in the discussed coatings is presented.

Properties of Fe-Al Type Intermetallic Layers Produced by AC TIG Method

ABSTRACT The paper presents the results of two new in-situ methods of Fe-Al intermetallic compounds layers fabrication on the steel substrates. The layers were produced by hardfacing of pure aluminum and titanium on the steel (S235JR) substrate as well as in the two-step process: the thermal spraying of pure aluminum on a steel substrate and subsequent remelting of aluminum coating with iron from the substrate using AC TIG method. As a result of the synthesis of Fe, Al and Ti components (for the hardfacing method) the new layer material based on the ordered intermetallic phases was achieved. The effects were confirmed by metallographic examinations, hardness tests and the diffraction patterns of the analyzed remelted layers. In addition, measurements of residual stresses in the layer and substrate were carried out.

The Numerical Analysis of Residual Stresses in Surface Layers Deposited by Brush-Plating Method

Abstract The brush-plating method utilizes the galvanic approach to deposit surface layers onto the metallic and non-metallic substrates. One of the difficulties related to this process is the problem of layer delamination by an unfavourable residual stress state. The residual stresses play an important role in the process of surface layer deposition and during subsequent service life. This paper presents the results of the FEM analysis of residual stresses in surface layers produced by the brush-plating method. The Cu, (Cu + Al2O3), Ni, (Ni + Al2O3) materials in the form of composites and continuous layers deposited on low-carbon steel were analysed and compared.

Microstructural studies and analysis of residual stresses in Co-TiC composites obtained by the spontaneous crystallization method

Microstructural studies and analysis of internal stresses in Co–TiC composites prepared by the spontaneous crystallization method (high-temperature solution technique) have been performed. Metallographic observations and X-ray phase analysis of the obtained Co–TiC composite ingots were carried out. The microstructure of the Co–TiC interface was studied using transmission electron microscopy and high-resolution transmission electron microscopy. The Co–TiC composites were also subjected to numerical analysis by the finite-element method. The presented results of calculations include the analysis of the state of internal stresses generated in the composite during its cooling from the crystallization temperature to room temperature. On the basis of these results the internal stress distribution and its level were determined for the obtained Co–TiC composites.

The role of welding in the remanufacturing process

The article presents the characteristics of the remanufacturing process, as well as the economic conditions and technical applications of these methods of regeneration of parts. It also describes the application of welding methods for creating repair coatings.

Experimental Investigation of Displacement/Strain Fields in Metal Coatings Deposited on Ceramic Substrates by Thermal Spraying

The paper presents the initial results of application of the high sensitivity grating interferometry (GI) method in order to measure the displacement and strain fields in copper and titanium coatings thermally sprayed onto alumina ceramic (Al2O3). The residual stresses had been relieved by iterative cutting method, which was applied twice. The displacement maps of u and v were measured after each cut and εxx and εyy maps were calculated. The results clearly show the presence of εxx strains relieved along the second cut. The comparison of both samples confirmed that residual strains in Ti/Al2O3 are more significant than in Cu/Al2O3 system. The result after relevant postprocessing had been supplemented with the sub-surface principal residual stresses measured in the selected point by the x-ray diffraction method and curvature measurements.

The effect of the interface profile on the residual stresses formed in thermally sprayed NiAl coatings on Al2O3 substrate; Wpływ kształtu granicy połączenia na naprężenia własne powstające w natryskiwanych powłokach nial na podłożu ceramiki Al2O3

The physical preparation of a surface material to be coated by the thermal spray processing plays very important role as it affects the bonding force between the coating and substrate. when the coating material has different thermal and physical properties than the substrate the thermal residual stresses are generated in a two material system which may reach the level that promotes the coating delamination or cracking. Another factor influencing the stress state in sprayed coatings may lay in the interface profile between the coating and substrate. we may try to affect this factor by analyzing the profile and texture of the substrate surface to be coated. This way we may influence the residual stress built in a deposited coatings. The aim of this paper is to model and analyze the effect of the substrate surface profile on the residual stresses generated during cooling of thermally sprayed metallic coatings onto the ceramic substrates. The numerical computer simulation has been performed to calculate and compare the residual stress state developed in thermally sprayed metallic/ceramic system (niAl/Al2O3). The main factor analyzed was the variation in the shape of the interface profile between the coating and substrate. The obtained results have been discussed.

Analiza porównawcza rozkładu temperatury i naprężeń podczas uderzenia cząstki ti w podłoże metalowe i ceramiczne podczas natryskiwania detonacyjnego; Comparative analysis of temperature and stress distribution upon Ti particle impingement in the substrate

The paper presents the results of stress and temperature distributions during thermal spraying of Ti particle onto Al 2 O 3 and Armco substrate. The �耀nite element model of dynamic impingement of Ti particle has been built and the displacement and penetration of the particle into the substrate material analyzed. The time dependent variation of stress and temperature were analyzed in points selected from the particle and substrate regions. The calculations have been performed for the two different particle speeds equaled 500 and 800 m/s. The results comparison analysis have been discussed.