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1
Content available Influence of Dissolved Oxygen Content on the Properties of Aqueous Milled WC-Co Powders
Chicinas Horea F., Marton Leó-Ede, Popa Catalin O.
Archives of Metallurgy and Materials
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2023
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Vol. 68, iss. 3
1205--1210
EN
The research aims to develop a novel and safer milling route to produce Hard Metals. Considering the risks associated with milling fine particles under organic solvents, especially the increased fire and explosion risks, we propose milling under aqueous milling media to diminish the risks associated with fire hazards, while maintaining the oxidation level at a minimum. The samples were sintered in an industrial sintering oven under vacuum at 1380°C subsequent to milling and drying. The characterisation of the materials has been done by X-ray diffraction, scanning electron microscopy, particle size analysis, optical microscopy, and a magnetometer. The obtained results indicate that appropriate properties of the powders after milling and drying as well as the desired biphasic (Co-WC) phases were obtained after sintering, thus proving the feasibility of such a route and diminishing specific fire hazards.
2
Content available Consolidation and Characterisation of Hard Metal Powders Milled under Dichloromethane
Chicinaș Horea, Jucan Ovidiu-Darius, Gădălean Rares Vasile, Conțiu Glad, Cotai Ana, Popa Catalin
Archives of Metallurgy and Materials
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2022
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Vol. 67, iss. 2
541--545
EN
This work presents the development of a safer processing route for hard metals. Traditional processing of fine particles under organic solvents presents significant explosion risks. The milling under dichloromethane (DCM) reduces the risks associated with fire hazards. After milling and drying, the samples have been sintered in an industrial sintering furnace under a vacuum at 1380°C. The materials’ characterisation has been done by X-ray diffraction, scanning electron microscopy, particle size analysis, optical microscopy, and by magnetic measurements. The present work results reveal the powders’ appropriate properties after milling and drying and the desired biphasic (Co-WC) phases obtained after sintering, thus proving the feasibility of such a route, therefore the diminishing of specific fire hazards.
3
Content available A Study On The Metal Carbide Composite Diffusion Bonding For Mechanical Seal
Kim D.-K., Shon I.-J., Song J., Ryu W.-J., Shin H.-Ch., Kwon E.-Y., Shin H., Kang S.-J.
Archives of Metallurgy and Materials
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2015
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Vol. 60, iss. 2B
1479--1483
EN
Mechanical Seal use highly efficient alternative water having a great quantity of an aqueous solution and has an advantage no corrosion brine. Metal Carbide composites have been investigated as potential materials for high temperature structural applications and for application in the processing industry. The existing Mechanical seal material is a highly expensive carbide alloy, and it is difficult to take a price advantage. Therefore the study of replacing body area with inexpensive steel material excluding O-ring and contact area which demands high characteristics is needed. The development of WC-Ni base carbide alloy optimal bonding composition technique was accomplished in this study. To check out the influence of bonding temperature and time, bonding characteristics of sintering temperature was experimented. The bonding statuses of this test specimen were excellent. The hardness of specimen and bonding rate were measured using ultrasound equipment. In this work, Powder of WC (involved VC, Cr), Co and Mo2C mixed by attrition milling for 24hours. Nanostructured WC-27.6wt.%Ni-1.5wt.%Si-0.11wt.%VC-1.1wt.%B4C composite were fabricated at 1190°C by high temperature vacuum furnace. To check out the influence of bonding temperature and time, bonding characteristics of sintering temperature was experimented. Its relative density was about 99.7%. The mechanical properties (hardness and fracture toughness) were 87.2 HRA and 4.2 M·Pam1/2, respectively. The bonding status of this test specimen was excellent and the thickness of bonding layer was 20 ~30§ at 1050 and 1060°C bonding temperature.
4
Content available remote Hardmetals characterization by tribological means
Ścieszka S. F., Grzegorzek W., Żołnierz M.
Journal of Achievements in Materials and Manufacturing Engineering
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2013
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Vol. 59, nr 2
86--98
EN
Purpose: The objectives of the paper are as follows. Firstly the presentation of new and reliable integrated testing method, in which conjoin action involving fracture and abrasion of hardmetals is carefully monitored and analysed, and secondly the evaluation of the empirical relationship between mass loss as a result of edge chipping during the initial transition stage of abrasive wear and fracture toughness in the form of formula. Design/methodology/approach: The tests were performed in a purpose-built testing machine. The apparatus consists of the disc rotating in the cylindrical chamber under normal force. The specimen bars, made from the hardmetals are attached to the upper side of the disc. The results from this testing show that by using one apparatus and one shape of the test specimen it is possible to obtain a reliable rating of hardmetals. Findings: The integrated testing method required a theoretical or empirical model which describes the relationship between fracture toughness, other mechanical properties and the test’s fracture indicator. The best correlation received was for empirical model based on study on abrasive wear by lateral cracking. Practical implications: The proposed method offers advantages when used in hardmetals development programmes to rank a large number of materials in terms of abrasion and fracture resistance. Originality/value: The innovative method enables the evaluation of abrasion and fracture resistance, one shape of specimen, and one testing procedure.
5
Content available remote Możliwości spajania węglików spiekanych ze stałą wiązką lasera
Mirski Z., Granat K., Stano S.
Przegląd Spawalnictwa
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2011
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R. 83, nr 12
15-20
PL
Połączenia spajane węglików spiekanych ze stalą powszechnie występują w produkcji narzędzi, stosowanych głównie w obróbce skrawaniem i w przemyśle wydobywczym. W artykule przedstawiono możliwości łączenia węglików spiekanych H10S i G10 ze stalą C45 za pomocą promienia lasera. Są to pierwsze, innowacyjne próby przeprowadzone w kraju. Połączenia pomiędzy węglikami spiekanymi i stalą wykonano jako bezpośrednie oraz przy zastosowaniu przekładek między łączonymi materiałami, wykonanych z miedzi, lutu 3-warstwowego Ag49/Cu oraz niklu. Próby spajania wykonano w Centrum Techniki Laserowej w Instytucie Spawalnictwa w Gliwicach. W tym celu zastosowano laser dyskowy TruDisk 12002 o mocy 12 kW, firmy Triumpf. Wiązka lasera ogniskowano najczęściej na powierzchni stali, aby nie doprowadzić do bezpośredniego oddziaływania lasera na strukturę węglików spiekanych. Ocenę złączy węglików spiekanych ze stalą C45 przeprowadzono na podstawie badań metalograficznych, analiz EDX i pomiarów mikrotwardości.
EN
Welded joints of hardmetals with steel are commonly present in manufacture of tools, mainly those used in the machining and in the mining industry. The paper presents possibilities of joining hardmetals H10S and G10 with steel C45 using laser radiation. These are first, innovative experiments carried-out in Poland. Joints between hardmetals and steel were made both directly and using spacers of copper, 3-layer filler Ag49/Cu and nickel between the materials to be joined. The trials were carried-out at Laser Technology Centre of the Polish Centre for Welding Technology in Gliwice. Applied was a disk laser Tru-Disk 12002 output power 12 kW made by Triumpf. The laser beam was basically focused on steel surface to avoid direct action of laser beam on hardmetal structure. Joints of hardmetals with C45 steel were evaluated on the grounds of metallographic observations, EDX analyses and microhardness measurements.
6
Content available remote Angle of incidence influence of abrasive particles on wear magnitude of hard facings metals
Jankura D.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
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2002
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z. 58 [193]
109-114
EN
The contribution presents the results of the research of resistance of hard facing metals in conditions of erosive wear. Two types of hard - surfacing electrodes with different chemical composition were used on creation of three layers hard facing metals. Chemical composition of electrodes determined difference in structure of surface deposit. We investigated the influence of angle of incidence of abrasive particles on wear magnitude of hard facing metals. The results of the experiments showed that intensity of wear is very depended on parameters of wear as well as structure morphology of hard facing metals.
7
Content available remote Badania właściwości użytkowych węglików spiekanych na podstawie identyfikacji stanu przejściowego zużycia
Ścieszka S. F., Filipowicz K.
Tribologia
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2000
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nr 4
755-769
PL
Przeprowadzono badania tribologiczne, w których skoncentrowano szczególną uwagę na stanie przejściowym z początkowego - niestabilnego etapu zużywania, gdzie dominował ubytek masy kontrolowany przez procesy pękania ostrza próbki, na ustabilizowany etap zużywania próbki kontrolowany przez procesy ścierania. Dokładna identyfikacja stanu przejściowego dla każdego gatunku węglika spiekanego była możliwa dzięki odpowiednio dobranemu kształtowi próbek oraz dzięki procedurze kontroli ubytku masy próbek w następujących po sobie kolejnych próbach zużywania. Na podstawie danych ilościowych ubytku masy próbek w etapie niestabilnym a następnie etapie stabilnym zużywania, wyznaczono parametry charakteryzujące odporność badanych węglików spiekanych na pękanie i na zużycie ścierne.
EN
Abrasive wear and brittle fracture lead to massive losses of function in drilling and mining equipment involving high replacement costs and extended downtime. In industrial processes involving direct impact and rubbing contact the main question remains unanswerednamely what is the optimal balance between wear resistance and fracture toughness of rock-bit hard metals.The apparatus and method presented in this paper night be able to fill this gap. During the course of this investigation the abrasive wear resistance and the fracture toughness of fifteen selected hard metals were evaluated. The apparatus used simulated the tribo-condition between drilling (mining) tools and the rock. The equation that enables calculation of the fracture toughness factor Kwr based on results from the carefully controlled repeated abrassion tests, is presented.
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