Tomasz Wróbel

Influence of magnetic field and inoculation on size reduction in pure aluminium structure

The main aim of this study was to determine common influences of two different refinement methods on EN AW-Al99,98 primary structure and developing of refinement mechanism. The first method is inoculation with small amount of (Ti+B) less than obligatory standard PN-EN 573-3 and the second method is influence of electromagnetic field on aluminium crystallisation process. These methods of structure refinement are particularly important in continuous and semicontinuous casting where products are used for plastic forming. Large columnar crystals zone result in forces extrusion rate reduction and during the ingot rolling delamination of external layers can occur. [Received on 30 March 2006; Accepted on 12 February 2007]

Characterization of Bimetallic Castings with an Austenitic Working Surface Layer and an Unalloyed Cast Steel Base

The paper presents the technology of bimetallic castings based on the founding method of layer coating directly in the cast process of the so-called method of mold cavity preparation. The prepared castings consist of two fundamental parts, i.e., the base and the working surface layer. The base part of the bimetallic casting is typical foundry material, i.e., unalloyed cast steel, whereas the working layer is a plate of austenitic alloy steel sort X2CrNi 18-9. The quality of the joint between the base part and the working layer was evaluated on the basis of ultrasonic non-destructive testing and structure examinations containing metallographic macro- and microscopic studies with the use of a light microscope (LOM) with microhardness measurements and a scanning electron microscope (SEM) with microanalysis of the chemical composition (energy dispersive spectroscopy—EDS). On the basis of the obtained results it was confirmed that the decisive phenomena needed to create a permanent joint between the two components of the bimetallic casting are carbon and heat transport in the direction from the high-carbon and hot base material which was poured into the mold in the form of liquid metal to the low-carbon and cold material of the working layer which was placed in the mold cavity in the form of a monolithic insert.

Indoor Location and Idetification of Objects with Video Survillance System and WiFi Module

There is an increasing demand for indoor navigation and localization systems along with increasing popularity of location based services in last years. The paper presents our work in progress for locating indoor objects based on signal fusion. The location is based on two signals: RSSI (Received Signal Strength Indication) and video camera. This paper presents a vision-based system for human detection and tracking in indoor environment using a single static camera. However its accuracy depends on calibration methods and additional sensors. Most of related works used very complex approach of calibration. In this paper actual position is calculated by simple algorithm with fast computing time.

Transformation of Pure Al Structure under the Influence of Electromagnetic Field

In paper problem concerning inoculation of primary structure of aluminum with purity of 99,5% and 99,8%, which is realized mainly by intensification of liquid metal movement in mould is presented. In aim of realization of forced movement during the crystallization of liquid metal was used rotating electromagnetic field produced by the induction coil supplied by current with elevated frequency. The degree of structure refinement was represented by equiaxed crystals zone content on transverse section of ingot and average area of macro-grain in this zone. Effect of structure refinement obtained by influence of electromagnetic field was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. titanium, boron and carbon to metal bath. The results of studies and their analysis show possibility of effective refinement of pure Al primary structure, only with use of rotating electromagnetic field and without necessity of application of inoculants such a Ti, B and C. This method of inoculation is important, because inoculants decrease the degree of purity and electrical conductivity of pure Al. Moreover Ti and B are reason of point cracks formation during rolling of ingots.

Bimetallic Castings in a Chromium–Nickel Stainless Steel Working Surface Layer Configuration with a Grey Cast Iron Base

The paper presents the problem of obtaining a permanent diffusion joint between the working surface layer and the base part in a bimetallic casting. The bimetallic castings studied here were obtained as a result of using the founding method of layer coating directly in the cast process, i.e., the so-called method of mould cavity preparation by monolithic insert. The castings prepared using this method consist of two fundamental parts, i.e., the base which constitutes typical foundry material, i.e., grey cast iron and the working surface layer which constitutes plate of chromium–nickel stainless steels, X2CrNi 18-9 and X2CrNiMoN22-5-3 grade. On the basis of the obtained results it was confirmed that the decisive phenomena that are needed to create a permanent joint between the two components of the bimetallic casting are carbon and heat transport in the direction from the high-carbon and hot base material which was poured into the mould in the form of liquid metal to the low-carbon and cold material of the working layer which was placed in the mould cavity in the form of a monolithic insert.

Indoor localization of objects based on RSSI and MEMS sensors

There is an increasing demand for indoor localization and tracking objects with high accuracy. The GPS system is not efficient for positioning in such areas. Rising number of smartphones allow for their utilization in indoor positioning system. RSSI (Radio Signal Strength Index) is commonly applied but it is limited to pattern matching methods. A map called fingerprint is created at the first stage. However its accuracy is low and very often not satisfying. Authors propose a method for indoor localization based on smartphone available sensors and RSSI system. First results shows positioning improvement and better accuracy with respect to commonly used RSSI map. The method introduces phone orientation with respect to AP (access point), direction of the object move. Results describe relatively low error of our method comparing to RSSI system.

Corrosion Resistance of Stabilizers for Funnel Chest Treatment

The paper presents results of physicochemical properties of the plates used for the treatment of pectus excavatum after implantation. Within the research, chemical analysis, macroscopic evaluation of the surface, electromechanical analysis, wettability and surface energy tests were conducted. On the basis of obtained results, it can be stated that the reduction of corrosion resistance is influenced by mechanical damage of the surface and laser marking, as well as by producing stabilizers made of various types of steel. This caused the decrease of corrosion resistance of the plate with reduced content od Cr, Ni and Mo. It was also stated that the analysed surfaces were hydrophilic with an average surface wettability, on which overgrowth of the tissue was not observed, which is an essential condition for short-term implants.

Assessment Of Hip Endoprosthesis Cups After Reimplantation

The paper presents results of the assessment of the absence of tissue hypertrophy to the surface of the hip endoprosthesis cups. The cups were obtained as a result of revision operations, which caused their loosening. The study included analysis of chemical composition, SEM, macroscopic evaluation of surface, pitting corrosion resistance and hardness. Based on the result obtained, it can be concluded that the surface condition of the outer part of the cups affects bone tissue hypertrophy to the ground.

The Influence of Electromagnetic Stirring on Primary Structure of Pure Al and Al-Si Alloy

In paper problem concerning inoculation of primary structure of Al with purity of 99,5% and 99,8% and AlSi2 alloy, which is realized mainly by intensification of liquid metal movement in mould is presented. In aim of realization of forced movement during the crystallization of liquid metal was used horizontal electromagnetic field produced by the induction coil (stirrer) supplied by current with elevated frequency. The degree of structure refinement was represented mainly by equiaxed crystals zone content on transverse section of ingot and average area of macro-grain in this zone. Effect of structure refinement obtained by influence of electromagnetic stirring was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. titanium, boron and strontium to metal bath. The results of studies and their analysis show possibility of effective refinement of pure Al and Al-Si alloy primary structure, only with use of horizontal electromagnetic field and without necessity of application of inoculants such a Ti and B. This method of inoculation is important, because inoculants decrease the degree of purity and electrical conductivity of pure Al. Moreover inoculants are reason of point cracks formation during rolling of ingots.

Inoculation of aluminium EN AW-Al99,5 structure

The main aim of studies was to determine common influences of two different refinement methods on EN AW-Al99,5 primary structure and developing of refinement mechanism. The first method is inoculation with small amount of (Ti+B) less than obligatory standard PN-EN 573-3 and the second method is influence of electromagnetic field on aluminium crystallisation process. These methods of structure refinement are particularly important in continuous and semi-continuous casting where products are used for plastic forming. Large columnar crystals zone result in forces extrusion rate reduction and during the ingot rolling delamination of external layers can occur. [Received 17 October 2006; Accepted 15 May 2007]