EFFECT OF TEST CONDITIONS ON WEAR PROPERTIES OF STEEL-MATRIX COMPOSITES

The friction coefficient and wear behavior of 316L austenitic stainless steel and 316L steel + 8vol% TiB2 + 1vol% B composites were investigated within a temperature range of 20°C to 800°C. The materials were prepared by the powder metallurgy method. The wear behavior was studied by using a ball-on-disc wear tester at room temperature. The surface before and after wear testswas analyzed using scanning electron microscopy (SEM). The results indicated that the friction coefficient and wear resistance of stel-8TiB2-1B composites depend on the wear test conditions

INFLUENCE OF ANNEALING CONDITIONS ON THE PROPERTIES AND MICROSTRUCTURE OF STEEL COMPOSITES

Samples made of AISI 316L stainless steel reinforced with 8 vol.% TiB2 particles were prepared using high pressure-high temperature (HP-HT) method. Next, the composites were annealed at temperature of 1200°C for different holding times.  The influence of annealing temperature and time on the properties and microstructure of AISI316L+8% vol.TiB2 composites was investigated. The structural studies showed formation of phases containing chromium, molybdenum and boron

MECHANICAL PROPERTIES AND CORROSION RESISTANCE OF CAST NiAl ALLOYS WITH THE ADDITION OF Ti

Results of compression and corrosion resistance tests of NiAl alloys with 1.0 and 2.0 wt.% of titanium are described. The compression tests conducted in a wide range of temperature and strain rate showed that increase of titanium content causes increase of brittleness at room temperature, while at higher temperatures an increase of hardness and strength is observed. The analysis of electrochemical corrosion resistance showed that the alloys containing Ti are characterized by considerable resistance to sulfuric acid VI, because the emerging titanium oxide prevents active solubilizing of the alloy. Besides, microstructure observations performed at various levels of deformation which allowed to identify mechanisms responsible for fracture of the studied alloys

The Influence of Pearlite Present in the Microstructure of GX120MnCr13 Cast Steel on Wear Resistance

The article presents the results of metallographic and tribological tests on GX120MnCr13 cast steel that was previously subjected to heat treatment (including solution treatment from 1100°C and isothermal holding at 250, 400, and 600°C for 100 hours). The temperatures of the isothermal holding process were selected in order to reflect the possible working conditions of the cast elements that can be made of this cast steel. Wear tests were carried out under dry friction conditions using the ball-on-disc method using a ZrO2 ball as a counter-sample. The tests were carried out with a load of 5 N. The influence of the long-term isothermal holding process on the microstructure of the tested cast steel was analysed by light and scanning microscopy; however, abrasion marks were also examined using a confocal microscope. Based on the tests conducted, it was found that in the microstructures of the sample after solution treatment and samples that were held in isothermal condition at 250 and 400°C, the grain boundary areas were enriched in Mn and Cr compared to the areas inside the grains. Pearlite appeared in the sample that was heated (or held in isothermal holding) at 600°C; its share reached 41.6%. The presence of pearlite in the austenitic matrix increased the hardness to 351.4 HV 10. The hardness of the remaining tested samples was within a range of 221.8–229.1 HV 10. Increasing the hardness of the tested cast steel directly resulted in a reduction in the degree of wear as well as the volume, area, and width of the abrasion marks. A microscopic analysis of the wear marks showed that the dominant process of the abrasive wear of the tested friction pair was the detachment and displacement of the tested material through the indentation as a result of the cyclical impact of the counter-sample

Pielęgniarstwo na rzecz milenijnych celów rozwoju

Praca recenzowana / Peer-reviewed paperPielęgniarki odgrywają kluczową rolę w realizacji milenijnych celów rozwoju włączając się w wiele zróżnicowanych działań na poziomie zarówno lokalnym, krajowym, jak i międzynarodowym. Są to działania m.in. o charakterze wychowawczo- edukacyjnym, opiekuńczo-terapeutycznym, badawczym, jak i politycznym. Przykładem takich działań jest materiał zawarty w niniejszej monografii, w której znalazły się wyniki dociekań naukowych prezentujące aktywność środowiska pielęgniarskiego na rzecz społeczności pacjentów w zdrowiu i w chorobie oraz na rzecz grupy zawodowej pielęgniarek, zmagającej się z wieloma problemami, których rozwiązanie ma istotny związek z realizacją funkcji zawodowych przedstawicieli tej profesji. Tematyka prac składających się na monografię Pielęgniarstwo na rzecz milenijnych celów rozwoju jest bogata i pokazuje różnorodność zainteresowań badawczych pielęgniarek, co nierozerwalnie wiąże się z wielowymiarowością roli społeczno- zawodowej pielęgniarki – także w kontekście realizacji przyjętych przez ONZ celów

Effect of Zirconium Diboride and Titanium Diboride on the Structure and Properties of 316L Steel-Based Composites

The effect of zirconium diboride (ZrB2) and titanium diboride (TiB2) on the microstructure as well as the physical, mechanical, and tribological properties of composites based on 316 L steel is presented. Each reinforcing phase was added to the base alloy in the amount of 5 wt% and 10 wt%. The composites were fabricated by the SPS process (Spark Plasma Sintering). The results show that the weight fraction of the reinforcing phase affects the physical, mechanical, and tribological properties of the sintered composites. The sintered materials were characterized by a very high level of density. The addition of TiB2 has proved to be effective in increasing the hardness and compressive strength of the composites. The hardness of the composites with the addition of 10% TiB2 increased by 100% compared to the hardness of sintered 316L steel. It was found that introducing ZrB2 to the steel matrix significantly improved the wear resistance of the composites. The results showed that compared to 316L steel with the wear rate of 519 × 10−6 mm3/Nm, the wear rate of the composites containing 10% ZrB2 decreased more than twice, i.e., to 243 × 10−6 mm3/Nm

Influence of annealing conditions on the properties and microstructure of steel composites Wpływ warunków wyżarzania na właściwości i mikrostrukturę kompozytów o osnowie stali austenitycznej /

Tyt. z nagłówka.Bibliogr. s. 42-[43].Samples made of AISI 316L stainless steel reinforced with 8 vol.% TiB2 particles were prepared using the high pressure-high temperature (HP-HT) method. Next, the composites were annealed at a temperature of 1200°C for different holding times. The influence of the annealing temperature and time on the properties and microstructure of AISI316L+8% vol.TiB2 composites was investigated. The structural studies showed the formation of phases containing chromium, molybdenum and boron.Głównym celem pracy było określenie wpływu temperatury oraz czasu wyżarzania na właściwości i mikrostrukturę kompozytów umacnianych ceramiką TiB2. Proces spiekania materiałów kompozytowych o osnowie stali austenitycznej przeprowadzono przy zastosowaniu spiekania wysokociśnieniowego-wysokotemperaturowego (HP-HT). Kompozyty były wyżarzane w temperaturze 1200°C w różnych czasach. Stwierdzono, że mikrotwardość oraz odporność na ścieranie obniża się już po 30 minutach wyżarzania. Badania mikrostrukturalne wykazały powstanie dużych faz zawierających chrom, molibden oraz bor.Dostępny również w formie drukowanej.SŁOWA KLUCZOWE: kompozyty, wyżarzanie, właściwości, dwuborek tytanu. KEYWORDS: composites, annealing, properties, diboride titanium

Processing and Properties of ZrB₂-Copper Matrix Composites Produced by Ball Milling and Spark Plasma Sintering

Copper matrix composites with zirconium diboride (ZrB2) were synthesised by ball milling and consolidated by Spark Plasma Sintering (SPS). Characterisations of the ball-milled composite powders were performed by scanning electron microscopy (SEM), X-ray diffraction, and measurement of the particle size distribution. The effect of the sintering temperature (1123 K, 1173 K, and 1223 K) and pressure (20 MPa and 35 MPa) on the density, porosity, and Young’s modulus was investigated. The relationship between the change of Orb content and physical, mechanical, and electrical properties was studied. Experimental data showed that the properties of Cu–Orb composites depended significantly on the SPS sintering conditions. The optimal sintering temperature was 1223 K with a pressure of 35 MPa. Composites exhibited a high degree of consolidation. For these materials, the apparent density was in the range of 93–97%. The results showed that the higher content of Orb in the copper matrix was responsible for the improvement in Young’s modulus and hardness with the reduction of the conductivity of sintered composites. The results showed that Young’s modulus and the hardness of the Cu 20% Orb composites were the highest, and were 165 GPa and 174 HV0.3, respectively. These composites had the lowest relative electrical conductivity of 17%