Wyniki wyszukiwania - Biblioteka Nauki

1

The influence of WC grain size on the durability of WCCo cutting edges in the machining of wood-based materials

100%

Wachowicz J. , Wierzbicka K. , Czarniak P.

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2019

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tom No. 107

65--71

EN

WCCo cemented carbides are one of the basic materials used for tools. They consist of tungsten carbide in 70–96% and a binding warp – cobalt. High hardness of these materials determines their high resistance to abrasive wear. These properties predispose them to be used as a material for cutting tools. This study presents the results of tests on the durability of cutting edges made of WCCo composite of different WC grain in the machining of wood-based materials. The tests showed a several-fold increase of the durability of edges made of WCCo composite of grain size of 0.2÷0.5 μm compared to WCCo blades of WC grain size of 0.5÷0.8 μm and 0.8÷1.3 μm.

PL

Wpływ wielkości ziarna WC na trwałość ostrzy skrawających wykonanych z kompozytu WCCo w obróbce materiałów drewnopochodnych. Węgliki spiekane WCCo są jednym z podstawowych materiałów narzędziowych. Składają się one w 70–96% z węglika wolframu oraz z osnowy wiążącej - kobaltu. Wysoka twardość tych materiałów decyduje o ich wysokiej odporności na zużycie ścierne. W pracy przedstawiono wyniki badań trwałości ostrzy skrawających wykonanych z kompozytu WCCo o rożnej wielkości ziarna WC, w obróbce materiałów drewnopochodnych. Badania trwałości, wykazały kilkukrotny wzrost trwałości ostrzy wykonanych z kompozytu WCCo, o wielkości ziarna 0,2÷0,5 μm w porównaniu do ostrzy WCCo o wielkościach ziarna WC 0,5÷0,8 μm oraz 0,8÷1,3 μm.

2

Microstructural and Mechanical Study of Inconel 625 - Tungsten Carbide Composite Coatings Obtained by Powder Laser Cladding

88%

Huebner J. , Rutkowski P. , Kata D. , Kusiński J.

Archives of Metallurgy and Materials

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2017

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tom Vol. 62, iss. 2A

531--538

EN

This study focuses on the investigation of fine (~0.54 μm) tungsten carbide particles effect on structural and mechanical properties of laser cladded Inconel 625-WC composite. Three powder mixtures with different Inconel 625 – WC weight ratio (10, 20 and 30 weight % of WC) were prepared. Coatings were made using following process parameters: laser beam diameter ø ≈ 500 μm, powder feeder rotation speed – 7 m/min, scanning velocity – 10 m/min, laser power – 220 W changed to 320 W, distance between tracks – 1 mm changed to 0.8 mm. Microstructure and hardness were investigated. Coatings produced by laser cladding were crack and pore free, chemically and structurally homogenous. High cooling rate during cladding process resulted in fine microstructure of material. Hardness improved with addition of WC from 396.3 ±10.5 HV for pure Inconel 625, to 469.9 ±24.9 HV for 30 weight % of WC. Tungsten carbide dissolved in Inconel 625 which allowed formation of intergranular eutectic that contains TCP phases.

3

Evaluation of cutting forces and temperature of iron-rich binder carbide tool in turning of titanium

88%

Mahadevaiah C. , Prasad S.

Engineering Transactions

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2018

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tom Vol. 66, iss. 3

325--338

EN

The machining of titanium has been understood to be challenging and costly due to its material properties such as low thermal conductivity, low modulus of elasticity, high strength at elevated temperatures and chemical reactivity. This work aims to study the effect of iron as a partial substitution along with cobalt binder as the tool material for machining of titanium alloy. In this work, iron-rich binder tool (WC-Co-Fe) and cobalt binder tool (WC-Co) samples were produced by powder metallurgy route using powders with a mean particle size of less than 0.5 µm. Next, the evaluation of mechanical properties and phase analysis were performed. Turning experiments were conducted at various cutting speeds, feed and depth of cut (DOC), to evaluate the effects of iron-rich binder on flank wear, cutting forces and cutting temperature. The obtained results of turning experiments reveal that iron-rich binder tends to increase cutting performance in comparison to conventional WC-Co composite cutting tools.

4

Surface roughness analysis in milling tungsten carbide with CBN cutters

88%

Twardowski P.

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tom Vol. 18, nr 1

105-114

EN

In this paper, an experimental surface roughness analysis in milling of tungsten carbide using a monolithic torus cubic boron nitride (CBN) tool is presented. The tungsten carbide was received using direct laser deposition technology (DLD). The depth of cut (ap), feed per tooth (fz) and tool wear (VBc) influence on surface roughness parameters (Ra, Rz) were investigated. The cutting forces and accelerations of vibrations were measured in order to estimate their quantitative influence on Ra and Rz parameters. The surface roughness analysis, from the point of view of milling dynamics was carried out. The dominative factor in the research was not feed per tooth fz (according to a theoretical model) but dynamical phenomena and feed per revolution f connected with them.

5

Synthesis and characterization of nanostructured molybdenum & tungsten carbide materials, and study of diffusion model

88%

Covington L. , Munirathinam K. , Islam A. , Roberts K.

Polish Journal of Chemical Technology

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2012

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tom 14

|

nr 1

28-34

EN

Powders of two molybdenum carbides (Mo2C and MoC1-x) and tungsten carbide (WC) were prepared by means of temperature programmed reaction (TPR) method. Mo2C and MoC1-x were synthesized by reacting MoO3 with a preselected molar ratio of methane/hydrogen and carbon monoxide/hydrogen gas mixtures respectively. WC was prepared using tungsten oxide (WO3) and a methane/hydrogen gas mixture. These carbides were ultrasonically dispersed in de-ionized water. Samples were characterized using room temperature x-ray diffraction and scanning microscopy. A kinetic diffusion model is also studied to determine diffusivities in solids where the diffusing species desorbs or reacts at the external surfaces, and where the diffusivity does not vary appreciably with concentrations. The method involves measuring the flux of the diffusive species into the solid under the influence of a temperature program.

6

Mechanical and thermal properties of tungsten carbide – graphite nanoparticles nanocomposites

88%

Kornaus K. , Gubernat A. , Zientara D. , Rutkowski P. , Stobierski L.

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tom Vol. 18, nr 2

84--88

EN

Previous studies concerning pure tungsten carbide polycrystalline materials revealed that nanolayers of graphite located between WC grains improve its thermal properties. What is more, pressure-induced orientation of graphene nano platelets (GNP) in hot pressed silicon nitride-graphene composites results in anisotropy of thermal conductivity. Aim of this study was to investigate if addition of GNP to WC will improve its thermal properties. For this purpose, tungsten carbide with 0.5–6 wt.% of GNP(12)-additive underwent hot pressing. The microstructure observations performed by SEM microscopy. The anisotropy was determined via ultrasonic measurements. The following mechanical properties were evaluated: Vickers hardness, bending strength, fracture toughness KIc. The influence of GNP(12) addition on oxidation resistance and thermal conductivity was examined. It was possible to manufacture hot-pressed WC-graphene composites with oriented GNP(12) particles, however, the addition of graphene decreased both thermal and mechanical properties of the material.

7

Diode Laser Surface Alloying of Armor Steel with Tungsten Carbide

88%

Janicki D. , Górka J. , Kwaśny W. , Gołombek K. , Kondracki M. , Żuk M.

Archives of Metallurgy and Materials

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2017

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tom Vol. 62, iss. 2A

473--481

EN

Metal matrix composite (MMC) surface layers reinforced by WC were fabricated on armor steel ARMOX 500T plates via a laser surface alloying process. The microstructure of the layers was assessed by scanning electron microscopy and X-ray diffraction. The surface layers having the WC fraction up to 71 vol% and an average hardness of 1300 HV were produced. The thickness of these layers was up to 650 μm. The addition of a titanium powder in the molten pool increased the wettability of WC particles by the liquid metal in the molten pool increasing the WC fraction. Additionally, the presence of titanium resulted in the precipitation of the (Ti,W)C phase, which significantly reduced the fraction of W-rich complex carbides and improved a structural integrity of the layers.

8

The Effects of Travel Speed of Tungsten Inert Gas Cladding of Tungsten Carbide and Nickel Composites on the Microstructure of Stainless Steel

75%

Oleiwi A. A. , Jilabi A. S. J.

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tom Vol. 18, no 4

177--190

EN

he scientific and industrial communities now consider surface modification of steel-based alloys to be essential. One effective method of altering these alloys' surfaces is tungsten inert gas (TIG) cladding.The purpose of this study is to investigate how the surface characteristics of austenitic stainless steel substrates are affected by TIG-deposited composite coatings made of tungsten carbide and nickel (WC-Ni). The study also intends to investigate the influence of the WC-Ni composite coatings' travel speed, and as a result, the heat input usually has significant effects on the microstructure. The coating layers were deposited at different travel speeds (67, 107, and 122 mm/min) using pre-placed composite pastes that were 1 mm thick and contained the same weight percentage of WC (65). The clad layers showed a variety of microstructures in optical and scanning electron microscopy, primarily nickel solid solution dendrites with WC particles scattered throughout the matrix. The dendrites at various locations across the clad layers were few or dense, finer or coarser, equiaxial or columnar, densely or less densely branched, depending on the cooling rates and the density of WC in the composite. Energy dispersive spectroscopy demonstrated that the Fe element that was transferred from the substrate material to the molten pool was primarily concentrated in the matrix, not the dendrites, while the dendrite locations and orientations were amply demonstrated by the distribution of the W element.

9

Spark Plasma Sintering – new technology for obtaining tool materials

75%

Wachowicz J.

|

tom 109

10

Mikrostruktura i właściwości mechaniczne nanostrukturalnych powłok WC12Co natryskanych naddźwiękowo

75%

Burakowski T. , Żórawski W.

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tom Vol. 31, nr 4

905-908

PL

Powłoka WC12Co została natryskana naddźwiękowo (HVOF) z proszku, którego ziarna zawierały nanometryczne cząstki węglika wolframu w osnowie kobaltowej. Nanostrukturalny proszek oraz natryskana powłoka były analizowane za pomocą mikroskopu elektronowego skaningowego (SEM) i mikroskopu elektronowego transmisyjnego (TEM). Stwierdzono, że w skład ziaren proszku oraz natryskanej powłoki wchodzą nanocząstki węglika wolframu. W przypadku kobaltu, ciepło naddźwiękowego strumienia natryskowego spowodowało utworzenie w wielu miejscach struktury amorficznej. Twardość powłoki natryskanej z proszku o budowie nanostrukturalnej, wynosząca 1159 HV, była wyższa o 20% niż powłoki natryskanej z proszku konwencjonalnego na takie samo podłoże. Powłoka nanostrukturalna miała również większą odporność na zużycie ścierne oraz mniejszą porowatość.

EN

Nanostructured cermet coating was sprayed from agglomerated nanostructured WC12Co powder feedstock by means of hypersonic spray process (HVOF). Grains of tungsten carbide nanopowder were analyzed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Investigations revealed that grains of powder and sprayed coating contain nanoparticles. In the case of cobalt matrix heat of the hypersonic stream cause create amprphous structure. Nanostructured sprayed coating exhibit hardness 1159 HV, which was 20 % higher than hardness of conventional coating sprayed on the same core. Nanostructured coating show higher wear resistance and lower porosity.

11

Skrawalność w procesie frezowania twardych napoin z węglika wolframu

75%

Twardowski P. , Wojciechowski S.

Mechanik

|

2010

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tom R. 83, nr 12

915-923

PL

Przedstawiono wpływ warunków skrawania: dosuwu osiowego ap, posuwu na ostrze fz i prędkości skrawania vc na skrawalność napoin z węglików wolframu (WC) przy zastosowaniu jako wskaźników skrawalności parametrów chropowatości powierzchni (Ra, Rz) oraz zużycia ostrza (VBc).

EN

Presented are specific effects caused by cutting process parameters viz: the effect of axial infeed ap, of the feed movement rate on cutting edge fz and the effect of cutting speed vc on machinability of the tungsten carbide weld material with the machinability indices determined through the surface finish parameters (Ra, Rz) and wear (VBC) of the cutting edge.

12

Computer Aided Quantitative Analysis of Advanced Ceramic Materials

75%

Górny G. , Rączka M.

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1999

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tom Vol. 47, nr 4

335-352

EN

The paper presents the results of the computer aided quantitative analysis of the three groups of the ceramic composites: [formulas]. The methods of visualization and processing were elaborated and the representative microstructural characteristics for these materials have been thus obtained. The relationship between the microstructure and parameters of synthesis can be thus studied.

13

Particulate Composites in the TZP-Carbide Systems

75%

Haberko K. , Pędzich Z.

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1999

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tom Vol. 47, nr 4

379-395

EN

The paper presents the results of investigations on particulate ceramic composites with the tetragonal zirconia polycrystalline (TZP) matrix. The WC, CrxCy and TiC particles were used as additives. The possibility of a chemical reaction in these systems was taken into account. Stresses caused by coefficient of thermal expansion mismatch of composite constituents were estimated. Phase composition and microstructure of the composite constituents were estimated. Phase composition and microstructure of the composites were described. Mechanical properties of the composites were measured and compared.

14

Struktura i właściwości mechaniczne hybrydowych powłok nc-WC/a-C:H

75%

Gawroński J. , Makówka M. , Pawlak W. , Kaczmarek Ł.

|

tom Vol. 34, nr 5

434--437

PL

W ostatnich latach daje się zaobserwować coraz większe zainteresowanie przemysłu motoryzacyjnego, lotniczego i AGD poprawą właściwości użytkowych odlewniczych stopów aluminium. O ile badania z zakresu modyﬁkacji powierzchni stopów Al przeznaczonych do przeróbki plastycznej z grupy 2024 i 7075 są prowadzone na świecie od wielu lat, o tyle w zakresie stopów odlewniczych Al, w szczególności siluminów, prace te są dopiero w fazie początkowej. W pracy wykonano badania na wybranym siluminie z naniesioną powłoką nc-WC/a-C:H metodą PVD, w temperaturze 150°C, atmosferze argonu, pod ciśnieniem 0,55 Pa oraz w zakresie mocy 0,2÷1,4 kW. Do nanoszenia powłok użyto targetów z wolframu i graﬁtu. Tak wytworzone powłoki badano pod względem przyczepności do podłoża, właściwości mechanicznych (nanotwardość, moduł Younga), tribologicznych (współczynnik tarcia, zużycie) oraz strukturalnych (EDS, XRD). W wyniku przeprowadzonych badań stwierdzono, że wytworzone powłoki metodą PVD na wybranym siluminie w znaczący sposób zwiększają jego właściwości użytkowe, co może przyczynić się do ich coraz szerszego zastosowania na części maszyn, w których jest wymagane zwiększenie odporności na ścieranie.

EN

In recent years it is observed increasing interest of automotive, aviation and power hydraulics industries of the use properties improvement of aluminium casting alloys. While the scientiﬁc research in the field of aluminium alloys surface modiﬁcation predicted for mechanical working - within the 2024 and 7075 groups - has been carried out all over the world since many years whereas in terms of casting aluminum alloys, in particular silumins, studies are at the very initial phase. In this work, tests were performed on the selected casted silumin with former deposited by PVD method nc-WC/a-C:H coating. Process conditions were: temperature of 150°C, argon atmosphere, pressure of 0.55 Pa and the power range of 0.2÷1.4 kW. The targets used for coating were tungsten and graphite. As deposited coatings were tested in terms of its adhesion to the substrate, mechanical properties (nanohardness, Young's modulus), tribological properties (friction coefﬁcient, wear) and structural properties (EDS, XRD). As a result it was found that deposited by PVD method coatings on the selected silumin significantly improve its performance and use properties which may contribute to their increasingly wider application wherever the need of increased wear resistance.

15

Zużycie ostrzy z regularnego azotku boru podczas wspomaganego laserowo toczenia twardej warstwy z węglików wolframu na osnowie niklowej

63%

Kieruj P. , Przestacki D. , Chwalczuk T.

|

2016

|

tom R. 89, nr 8-9

1136--1137

PL

Zaprezentowano analizę zużycia ostrzy podczas toczenia wzdłużnego węglika wolframu na osnowie niklowej oraz wpływ obróbki hybrydowej na trwałość ostrzy. W badaniach analizowano skrawność ostrzy z regularnego azotku boru (KB9610). Stwierdzono kilkukrotne zwiększenie trwałości ostrza podczas toczenia w warunkach wspomagania laserowego.

EN

This paper presents the analysis of tool’s flank wear during longitudinal turning of tungsten-carbides based on nickel matrix. The influence of hybrid machining was presented. The cutting inserts made of cubic boron nitride (KB9610) were applied in the research. The several times increase in tool life when turning under laser assisted conditions was found.

16

Simultaneous abrasion and edge fracture resistance estimation of hard materials by the tribotesting method

63%

Ścieszka S. F.

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2011

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tom Vol. 46, nr 2

55-104

EN

Fracture toughness and wear resistance are two of the major material characteristics to take into consideration when designing tools, particularly inserts for rotary and percussion rotary drilling, inserts for mining shearer picks and rotary picks made of hardmetals (WC-Co cemented carbides). This is mainly due to the high risk of brittle fracture in tools made of these materials and due to the importance of resistance to abrasion where the contact pressure between the component and abrasive is high as in mining and rock drilling. WC-Co hardmetals are materials that combine high abrasion resistance and hardness with rather low levels of toughness as a consequence of their microstructure. Nevertheless, the main problem facing designers remains the fact that the tungsten carbide and other cermetal tools may exhibit sudden brittle fracture. Since fracture toughness is often the major limiting parameter governing the use of WC-Co drilling and cutting tools, there is a need for research aimed at increasing toughness without sacrificing wear resistance. To aid in this objective, a simple and reliable integrated testing method, such as that presented in this paper, is needed for quick assessment of progress in such research. There are several methods for the measurement of fracture toughness, although there is no standard method for hardmetals. The single edge pre-cracked beam method and the chevron notch method (both proposed by the ASTM) are most commonly used despite the fact that they are rather expensive and laborious. Problems connected with the effective and reliable use of these experimental methods has stimulated efforts towards the following: firstly, the development of empirical and semi-empirical formulae describing the relationship between the critical stress intensity factor (KIC) and other mechanical and physical properties that are much easier to evaluate; and, secondly, the development of new toughness evaluation methods based on edge damage pattern. One such method currently evolved by the Tribotechnology Division at Silesian University of Technology is the subject of further, more advanced study together with the Institute for Sustainable Technologies, Radom. The method is based on the concept of edge chipping in the initial transition stage of abrasion wear, which is controlled by the brittle fracture process. The method of testing is seen as a promising and pragmatic way of ranking hard materials for fracture toughness and wear resistance. The limitations of the method for tougher materials such as novel hardmetals and ceramics are investigated in this paper.

PL

Odporność na pękanie i odporność na zużycie ścierne są dwoma głównymi parametrami charakteryzującymi materiały stosowane na narzędzia, takie jak np. wiertła, noże kombajnów ścianowych i chodnikowych. Ostrza tych narzędzi wykonuje się obecnie głównie z węglików spiekanych (WC-Co). Znaczenie ww. parametrów jest konsekwencją udziału dwóch głównych mechanizmów uszkodzeń prowadzących do utraty zdatności eksploatacyjnej tych narzędzi, czyli pękania ostrzy oraz ich zużycia ściernego w kontakcie ze skałą w trakcie wiercenia lub urabiania przez skrawanie. Ponieważ odporność na pękanie i zużycie ścierne decydują o właściwym doborze materiałów na ostrza narzędzi, potrzebna jest do oceny tych materiałów metoda badawcza integrująca oba główne mechanizmy uszkodzeń. Metodę taką oraz jej praktyczne zastosowanie przedstawiono w tym artykule. Znanych jest kilka metod pomiaru odporności na kruche pękanie, chociaż żadna z nich nie została uznana za standardową dla węglików spiekanych. Stosowana jest np. metoda SEPB (Single Edge Pre-cracked Beam) oraz metoda CNB (Chevron Notched Beam), chociaż obie te metody są raczej pracochłonne dla materiałów kruchych. Trudności związane z efektywnym i niezawodnym zastosowaniem dla twardych i kruchych materiałów eksperymentalnego wyznaczania odporności na pękanie (KIC) w warunkach płaskiego stanu odkształcenia spowodowały poszukiwanie metod alternatywnych. Jedna z takich metod, obecnie opracowywana w Politechnice Śląskiej, jest przedmiotem dalszych badań rozwojowych razem z Instytutem Technologii Eksploatacji w Radomiu. W tym artykule są przedstawione wstępne wyniki tej pracy oraz wcześniejsze badania własne autora.

17

The oxidation of WC-Co knives in wood extract

63%

Barlak M. , Wilkowski J. , Ostrowski K. , Werner Z. , Zagorski J.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2021

|

tom 114

18

Porównanie struktury i własności stali narzędziowej do pracy na gorąco stopowanej cząstkami TiC i WC

63%

Dobrzański L. A. , Labisz K. , Jonda E. , Klimpel A.

Archiwum Odlewnictwa

|

2006

|

tom R. 6, nr 21/1

117-124

PL

W pracy przedstawiono wyniki badań struktury oraz twardości stali narzędziowej do pracy na gorąco 32CrMoV12-28 stopowanej węglikiem wolframu oraz tytanu. Badania przeprowadzono przy użyciu nowoczesnego lasera dużej mocy HPDL. Stwierdzono zmiany struktury polegające na jej rozdrobnieniu, a także wzrost twardości w porównaniu do stali nie obrobionej laserowo. Określono wpływ parametrów obróbki laserowej na strukturę i twardość materiału.

EN

The laser treatment as a part of the new generation techniques applied in metal surface technology is discussed in this paper. Laser treatment is presented with remelting of hot work tool steel 32CrMoV12-28 with ceramic powders, especially TiC Titanium Carbide and WC Tungsten Carbide. The structure investigation, and improvement of mechanical properties, is the practical aim of this work, as well as improvement of hardness as a very important property for practical use.

19

Glikol etylenowy bezposrednio z celulozy

63%

W O.

|

nr 1-2

74

20

Zużycie abrazyjne kompozytów ziarnistych na osnowach tlenkowych

63%

Pędzich Z.

Kompozyty

|

2008

|

tom R. 8, nr 4

403-408

PL

Opisano różnice w mechanizmach zużycia ściernego "na mokro" (test Millera) i "na sucho" (Dry Sand Test) kompozytów na osnowach dwóch podstawowych tlenków stosowanych jako materiały konstrukcyjne - tlenku glinu (odmiana [alfa], korund) oraz dwutlenku cyrkonu (faza tetragonalna, stabilizowana tlenkiem itru). Zastosowano dwa typy fazy wzmacniającej - tlenek lub węglik wolframu. Zmierzono wartości podatności na zużycie ścierne obu osnów i kompozytów. Analiza powierzchni próbek po testach pozwoliła stwierdzić, że dodatek wtrąceń modyfikuje znacząco mikrostrukturę osnowy tlenku glinu. Powoduje to zmianę dominującego mechanizmu zużycia i podniesienie odporności na ścieranie. Właściwości obu typów kompozytów są zdecydowanie różne w zależności od środowiska pracy.

EN

The paper describes differences in wear mechanisms between tests conducted in dry and wet environments (Dry Sand Test and Miller Test) for composites with two matrices: [alpha]-alumina and tetragonal zirconia. Two types of reinforced phase were used - the oxide and tungsten carbide particles. The wear susceptibility values were measured for matrices and composites. The worn surface analysis allows to establish that second phase particle addition modifies significantly alumina microstructure. It causes the change of dominant wear mechanism and increases wear resistance. Wear properties of both composite types are distinctly different in spite of wear environment. It was established that incorporation of second phase grains into alumina matrix influences wear properties changes in high scale. Changes observed for zirconia based composites are not so spectacular but still significant. Results of performed tests suggest that investigated materials are predicted to work at different environments. The wear at wet environments seems to be the best area of application for zirconia composites. Alumina based materials show the best properties during dry abrasion. Performed wear tests show the difference in the efficiency of application particular inclusion type. Although, incorporation of carbide grains always improves composite properties, the best scale of the improvement is achieved when one use oxide inclusions - zirconia grains into alumina matrix and on the contrary, alumina grains into zirconia matrix. It couldn't be simple described to differences in phase properties because one can observe differences between the agglomeration level of carbide and oxide inclusions. Such microstructural differences cold be an important factor of property diversification.