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EN
We construct via forcing a model for the level by level equivalence between strong compactness and supercompactness in which both V=HOD and the Ground Axiom (GA) are true. In our model, various versions of the combinatorial principles □ and ♢ hold. In the model constructed, there are no restrictions on the class of supercompact cardinals.
EN
The main objective of the present work was to determine the effect of powder composition on microstructure and properties of iron-base materials used as matrices in diamond impregnated tools. The Fe-Cu-Ni powders premixed and ball-milled for 30 hours, were used for the experiments. The influence of manufacturing process parameters on microstructure and mechanical properties of produced sinters was investigated. Sintering was done by hot-pressing technique in graphite mould. The powders were consolidated to a virtually pore-free condition during 3 minutes hold at 35 MPa and 900°C. Investigations of the sintered materials included: density, hardness, static tensile test and X-ray diffraction (XRD) analysis. Microstructural and fractographic observations were also made with a scanning electron microscope (SEM). The obtained results indicate that the sintered parts have a high density, close to the theoretical value, good plasticity, relatively high hardness and yield strength, and are characterized by a coarse-grained microstructure.
PL
W artykule przedstawiono zagadnienie bezpośredniego lutowania diamentu do korpusu narzędzia. Omówiono największe zagrożenia dla złącza lutowanego, takie jak naprężenia i zła zwilżalność. Następnie zaprezentowano wytwarzanie półfabrykatów z polikrystalicznego diamentu różnymi metodami. Dalej przedstawiono stopy metali (lutowia) o osnowie ze srebra, z niklu i miedzi, które wykorzystuje się do lutowania diamentu. Omówiono najczęściej stosowane metody lutowania twardego (oporowe, indukcyjne, laserowe i w poczerwieni).
EN
The article presents the problem of direct brazing of diamond to the tool body. The greatest threats to the brazing joint were discussed: stress and poor wettability. Methods for producing polycrystalline diamond blanks by various methods were presented. The metal alloys (solders) with a silver, nickel and copper matrix that is used for brazing diamonds were described. The most commonly used brazing methods (resistance, induction, laser and infrared) were discussed.
EN
The composition of the surface of natural diamonds in interaction with kimberlite minerals and the aqueous phase in the deposit and enriched ore is studied. The sequence and conditions for the formation of minerals on the surface of crystals under conditions of processing of kimberlites have been determined. Confirmed the mechanism of hydrophilization of diamonds comprising crystallization of hydroxides and oxides of iron as a mandatory initial stage. A method of destruction or subsequent dissolution of minerals aggregates by the impact of electrolysis products of aqueous systems has been proposed, which allows to restore the hydrophobicity of diamonds. The use of electrochemically treated water in the froth separation cycle with high diamond recovery made it possible to increase their recovery in the factory’s concentrate by 8.8%.
PL
Zbadano skład powierzchni naturalnych diamentów w interakcji z minerałami kimberlitowymi i fazą wodną w złożu i wzbogaconej rudzie. Określono kolejność i warunki tworzenia minerałów na powierzchni kryształów w warunkach przetwarzania kimberlitów. Potwierdzono mechanizm hydrofilizacji diamentów obejmujący krystalizację wodorotlenków i tlenków żelaza jako stały etap początkowy. Zaproponowano sposób niszczenia lub późniejszego rozpuszczania agregatów minerałów przez wpływ produktów elektrolizy układów wodnych, co pozwala przywrócić hydrofobowość diamentów. Zastosowanie elektrochemicznie uzdatnionej wody w procesie separacji piany z wysokim odzyskiem diamentu umożliwiło zwiększenie odzysku w koncentracie o 8,8%.
EN
This paper presents the results of research of Ni/diamond composite coatings produced by electrochemical reduction method. Research was focused on composite coatings with nickel matrix and diamond as a disperse phase and for comparison purposes on nanocrystalline nickel coatings. Ni/diamond composite coatings were produced in baths with different content of nanodiamond powder. The structures of the dispersed phase and the composite coatings were analysed by using X-ray diffraction, scanning electron microscopy and light microscopy. Measurements of selected properties of the coatings were performed, including roughness, microhardness, adhesion and abrasive wear resistance. The research results indicate that the produced coatings have a compact structure and good adherence to steel substrate. Moreover, nanocrystalline Ni/diamond composite coatings exhibit greater hardness and reduced abrasive wear resistance compared to nanocrystalline nickel coatings.
PL
W pracy przedstawiono wyniki badań własności mechanicznych spieków otrzymanych z mieszanki elementarnych proszków żelaza, miedzi i niklu poddanych mieleniu w młynie kulowym przez okres 60 godzin. Spieki wykonano techniką prasowania na gorąco w grafitowej matrycy. Zastosowano następujące parametry wytwarzania: ciśnienie 35 MPa, temperatura 900 °C, czas 3 minuty. Badania otrzymanych spieków obejmowały: pomiar gęstości, porowatości, twardości i statyczną próbę rozciągania. Dokonano również obserwacji mikrostruktury i przełomów zerwanych próbek przy użyciu elektronowego mikroskopu skaningowego (SEM). Badania prowadzono w celu określenia przydatności wytworzonych kompozytów do produkcji narzędzi metaliczno-diamentowych. Zbadano wpływ składu chemicznego, warunków procesu wytwarzania na mikrostrukturę i własności mechaniczne wytworzonych spieków.
EN
The paper presents the results of investigations of mechanical properties of sinter obtained from a mixture of elementary iron, copper and nickel powders milled in a ball mill for a period of 60 hours. Sintering was done by hot-pressing technique in graphite matrix. The following manufacturing parameters were used: pressure 35 MPa, temperature 900 °C, time 3 minutes. Investigations of the obtained sinterings included: density, porosity, hardness and static tensile test. Observations were also made of microstructure and fracture surface of broken samples using an electronic scanning electron microscope (SEM). The study was conducted to determine the suitability of manufactured composites for the manufacture of metal-diamond tools. The influence of chemical composition, microstructure and mechanical properties of the produced sinters was investigated.
7
Content available remote Diamond side resonances: influence of isotopic substitution of carbon
EN
We discuss the side resonances of the optically detected magnetic resonance in a diamond crystal and propose a new approach to the calculation of the hyperfine interaction in a composed system consisting of a negatively charged nitrogen-vacancy NV- center and a nearby 13C nuclear spin. The energy levels, rule selection and radiative transitions are obtained by a new method. The base of this method is the use of a complete set of commuting operators and entangled spin states. An estimation of the carbon hyperfine splitting parameters in the diamond NV- center from side-resonance frequencies is obtained in the frame of this method.
PL
Przedstawiono właściwości materiałów supertwardych, takich jak diament i regularny azotek boru, oraz ich zastosowanie na ostrza skrawające. Omówiono przykłady narzędzi z ostrzami z tych materiałów oraz wskazano na efektywność technologiczną i ekonomiczną wykorzystania tych narzędzi. Pierwsza część artykułu dotyczy materiałów i narzędzi z ostrzami diamentowymi, a druga – z ostrzami z regularnego azotku boru.
EN
The properties of super-hard materials such as diamond and regular boron nitride, and their application on cutting blades. Discussed are examples of blade tools from these materials in the aspects of production process efficiency and economical advantages gained by using these tools. The first part of the article deals with materials and tools with diamond blades and the other – with the blades of a regular boron nitride.
9
Content available remote Narzędzia skrawające z materiałów supertwardych. Cz. I. Ostrza diamentowe
PL
Przedstawiono właściwości materiałów supertwardych, takich jak diament i regularny azotek boru, oraz ich zastosowanie na ostrza skrawające. Omówiono przykłady narzędzi z ostrzami z tych materiałów oraz wskazano na efektywność technologiczną i ekonomiczną technologii wykorzystujących te narzędzia. Pierwsza część artykułu dotyczy materiałów i narzędzi z ostrzami diamentowymi, a druga – z ostrzami z regularnego azotku boru.
EN
The properties of super-hard materials such as diamond and regular boron nitride, and their application on cutting blades. Discussed are examples of blade tools from these materials in the aspects of production process efficiency and economical advantages gained by using these tools. The first part of the article deals with materials and tools with diamond blades and the other – with the blades of a regular boron nitride.
EN
This study presents properties of Ni3Al–diamond composites sintered by Pulsed Plasma Sintering (PPS) with the participation of SHS reaction (Self-propagating High-temperature Synthesis). Ni3Al–diamond sinters were produced using Ni:Al (3:1 at.) powder mixtures with addition of 30 vol. % of diamond with grain size ranging from 16 to 60 μm. The sintering process was performed at 1000°C in 5 minutes under load of 100 MPa. Obtained sinters have above 99% theoretical density and show fine crystalline microstructure with relatively uniformed diamond particles, what can be observed in SEM images of polished and fracture surface. The fractures are brittle and have the intergranular character. The X-ray phase examinations have shown that each sinter contains Ni3Al, diamond and Ni3C. The sinters hardness was tested by the Vickers method and oscillated between 580 and 650 HV5. The average grain size of Ni3Al matrix in obtained composites ranged from 2.6 to 3.8 μm.
PL
Rosnące zapotrzebowanie na różnego rodzaju narzędzia skrawające skłania do poszukiwania nowszych i bardziej wytrzymałych materiałów. W przypadku narzędzi diamentowych, tj. takich z dyspersyjnie rozmieszczonymi cząstkami diamentu, bardzo ważną rolę odgrywa osnowa. Najczęściej stosowaną osnową są związki na bazie kobaltu i żelaza. Jednak ze względu na cenę, a przede wszystkim rakotwórczy wpływ na zdrowie, dąży się do wyeliminowania kobaltu. Materiałem mogącym go zastąpić mogą być związki z układu Ni–Al. Dużym zainteresowaniem naukowców w ostatnich latach cieszą się spiekane kompozyty Ni3Al z dodatkiem cząstek TiB2, TiC lub SiC.
EN
Piston – ring – cylinder assembly of combustion engine has a lot of friction pairs examples, also one of them which decide about fastness to wear, it means first sealing ring – cylinder, called further very simply ring – cylinder unit. During work of this unit we can observe wear of piston, precisely – of coating which is deposited on ring to prolong service life. Objective of this work was to realize a test of roll-block type on tribotester to set durability of piston sample. Within the framework of this test were investigated a prototyped piston’s rings with diamond embankment. Piston rings are made of diamond coating technology with a porous chromium coating, where in pores is deposited on said diamond powder with a grain size about 1 micron. The work will be carried out of an analysis of collaboration piston – rings – cylinder unit in internal combustion engine and an analysis of the use of hard materials in friction pairs, including powders. The work aims to show the possibilities and benefits of the application of new protective coatings to reduce their wearing, which is consistent with the observed trend of technology development.
PL
W artykule przedstawiono metodę precyzyjnej obróbki stosowaną do uzyskiwania powierzchni o najwyższej jakości oraz o wysokim stopniu połysku. Proces mikrowygładzania realizuje się z wykorzystaniem diamentowych folii ściernych. Cechą charakterystyczną metody jest jednokrotny kontakt ziaren ściernych z powierzchnią obrabianą. Przedstawiono wyniki badań procesu mikrowygładzania stali o wysokiej twardości oraz zaproponowano podstawy prognozowania cech stereometrycznych wygładzonych powierzchni.
EN
The paper p resents a method for precise treatment used to obtain a high quality surface and high gloss. Microfinishing is carried out by using abrasive diamond films. A characteristic feature of the method is a single contact of abrasive grains with the surface of the workpiece. This article presents the results of studies of micro-finishing of high-hardness steel and proposes the foundations of forecasting of stereometric features of the finished surfaces.
EN
This paper describes the methodology and results of research on the tribological characteristics of the surfaces of diamond abrasive films using a stereometric analysis. Abrasive films are used in various finishing processes of surfaces with very high smoothness and accuracy. A morphological analysis of surface vertexes in the plane that is parallel to the film surface and the perpendicular direction allowed an assessment of the distances between particles by means of a decomposition of the surface into Voronoi cells. When studying the formation of the aggregates of diamond particles and the spaces between them, one may infer about the machining potential of the abrasive film and determine the recommended kinematic conditions of the film that ensures the maximum use of this potential. Owing to the investigations related to the morphology of diamond abrasive films, one can observe relevant characteristic abrasive aggregates that vary in term of size and shape depending on particle sizes. Units with elongated shapes have a superior machining ability in relation to spherical-shaped units. One of significant parameters proposed that describe the technological potential of abrasive films is the edge length to width ratio of diamond units. Different operating modes are discussed. A statistical analysis of the dynamics observed of abrasive interfaces allowed a pertinent description of the abrasive process taking into consideration nominal and apparent as well as abrasively efficient morphologies.
EN
This paper discusses the mechanical properties of a material fabricated from commercially available metal powder mixtures designed for use as a metal matrix of diamond impregnated composites. The mixtures with the catalogue numbers CSA and CSA800 provided by a Chinese producer are suitable for experimental laboratory testing. The specimens were fabricated in a graphite mould using hot pressing. The material was tested for density, porosity, hardness, and tensile strength under static loading. A scanning electron microscope (SEM) was used to analyze the microstructure and cleavage fracture of broken specimens. It was essential to determine how the chemical composition and the fabrication process affected the microstructure and properties of the material. The properties of the sinters were compared with those of hot pressed specimens fabricated from sub-micron size cobalt powder (Cobalt SMS). Although the as-consolidated material is inferior to cobalt, it displays a favourable combination of hardness, yield strength and ductility, and seems to have a great potential for moderate and general purpose applications.
PL
Przedstawiono wyniki badań szlifowania stali nierdzewnej 1H12N2MVFBA ściernicą z diamentu i CBN. Określono wpływ materiału ściernego na parametry eksploatacyjne części przy tarciu ślizgowym i procesach korozyjno-zmęczeniowych.
EN
In the paper experimental researches of grinding of stainless steel 1H12N2MVFBA CBN and diamond grinding wheel were presented. The influence of grinding parameters on the resistance of steel under sliding friction and corrosion fatigue processes is show. The development finishing treatment is given more effective in place of traditionally applied - electro-corundum grinding with next stabilizing tempering and mechanical polishing.
PL
Obecnie trwają prace nad zastąpieniem osnowy z drogiego i rakotwórczego kobaltu w kompozytach metal–diament materiałem na bazie faz międzymetalicznych z układu Ni–Al. W pracy przedstawiono wpływ wielkości cząstek diamentu na właściwości kompozytów Ni3Al–diament otrzymanych metodą impulsowo- plazmową (PPS) z udziałem reakcji SHS (Self-propagating Hight-temperature Synthesis). Do mieszaniny proszków Ni:Al w proporcji 3:1 dodano 30% obj. proszku diamentu o rozmiarze cząstek 16÷20 oraz 40÷60 μm. Następnie próbki spiekano w temperaturze 900°C przez 5 minut pod ciśnieniem prasowania 100 MPa. Otrzymane spieki wykazują gęstość względną powyżej 98% i charakteryzują się drobnokrystaliczną strukturą z równomiernie rozmieszczonymi cząstkami diamentu, co potwierdzają obserwacje powierzchni zgładów i przełomów za pomocą skaningowego mikroskopu elektronowego. Charakter przełomów jest kruchy, a mechanizm pękania międzykrystaliczny. Kompozyty Ni3Al–diament poddano także badaniu rentgenowskiej analizy fazowej, która poza fazą Ni3Al i diamentem wykazała obecność fazy Ni3C, bez względu na wielkość zastosowanego diamentu. Twardość Vickersa wynosiła 578±9 HV5 dla spieku Ni3Al–diament 16÷20 μm oraz 606±2 HV5 dla spieku Ni3Al–diament 40÷60 μm. Spieki Ni3Al–diament poddano badaniom odporności na zużycie przez tarcie metodą kula–tarcza. Zużycie kompozytów diamentowych jest znikome i praktycznie niemierzalne. Spiek z diamentem o cząstkach 40÷60 μm charakteryzował się mniejszym współczynnikiem tarcia niż spiek Ni3Al–diament 16÷20 μm. Podsumowując, wielkość cząstek diamentu zastosowanego w kompozytach Ni3Al–diament nie wpływa na mikrostrukturę. Zauważalnie zwiększają się właściwości mechaniczne (twardość, odporność na ścieranie) z zastosowaniem diamentu o większych cząstkach 40÷60 μm.
EN
There is an increasing number of research studies with aim to eliminate carcinogenic and expensive cobalt from metal–diamond composites and replace it by Ni–Al intermetallic phases. This study presents the influence of diamond particle size on the properties of Ni3Al–diamond composites sintered by Pulsed Plasma Sintering (PPS) with the participation of SHS reaction (Self-propagating High-temperature Synthesis). Ni3Al–diamond sinters were produced using Ni:Al (3:1 at.) powder mixtures with addition of 30% vol. of diamond with grain size ranging from 16 to 60 μm. The sintering process was performed at 900°C in 5 minutes under load 100 MPa. Obtained sinters have above 98% theoretical density and shows fine crystalline microstructure with relatively uniformed diamond particles, what can be observed on SEM images of polished surface and fracture. The fractures are brittle and have the intergranular character. The X-ray phase examinations have shown that each sinters contains Ni3Al, diamond and Ni3C. Hardness of the sinters was tested by the Vickers method and was 578±9 HV5 for Ni3Al–diamond 16÷20 μm sinter and 606±2 HV5 for Ni3Al–diamond 40÷60 μm. Wear resistance of Ni3Al–diamond sinters, tested by ball-on-disc method, showed that wear ratio is non-measurable and Ni3Al–diamond 40÷60 μm sinter has much lower friction factor than Ni3Al–diamond 16÷20 μm. Presented research has shown no influence of diamond particle size used in Ni3Al–diamond sinters on structural properties, however an increase of mechanical properties in composite with diamond 40÷60 μm can be noticed.
PL
W pracy przedstawiono wyniki badań trwałości ostrzy skrawających wykonanych z kompozytu o osnowie WC6%Co, zawierającego 30% obj. rozproszonych cząstek diamentu o gradacji 8-10 µm lub 16-20 µm. Kompozyty spiekano w urządzeniu PPS (ang. pulse plasma sintering), opracowanym na Wydziale Inżynierii Materiałowej Politechniki Warszawskiej, w temperaturze 1050 °C, w czasie 5 min i przy ciśnieniu prasowania wynoszącym 100 MPa i 120 MPa, w zależności od wielkości cząstek diamentu. Otrzymane spieki posiadały gęstość zbliżoną do teoretycznej (powyżej 99% GT) oraz twardość HK1 na poziomie ok. 2000. Badania trwałości, w procesie skrawania materiału MDF o gęstości 720-750 kg/m3, wykazały ponad ośmiokrotny wzrost trwałości ostrzy wykonanych z kompozytu WC6%Co z diamentem 16-20 µm w porównaniu do ostrzy wykonanych z handlowego węglika spiekanego HM.
EN
The paper presents the results of durability tests of cutting blades made of composites containing WC6%Co and 30 vol.% of diamond particles of 8-10 µm or 16-20 µm in size. The composites were sintered by using the PPS method (Pulse Plasma Sintering), which has been developed at the Faculty of Materials Science and Engineering at the Warsaw University of Technology. The sintering process was conducted for 10 minutes at a temperature of 1050 °C under a pressure of 100 MPa or 120 MPa, depending on the size of diamond particles. The composites had a density close to the theoretical one (more than 99% TD) and a hardness HK1 of 2000. Cutting tests were carried out on MDF with a density of 720-750 kg/m3. Blades of composite material: WC6%Co with the 16-20 µm diamond showed the lifetime more than eight times longer when compared to the HM cemented carbide blades.
EN
In situ monitoring of the thickness of thin diamond films during technological processes is important because it allows better control of deposition time and deeper understanding of deposition kinetics. One of the widely used techniques is laser reflectance interferometry (LRI) which enables non-contact measurement during CVD deposition. The authors have built a novel LRI system with a 405 nm laser diode which achieves better resolution compared to the systems based on He-Ne lasers, as reported so far. The system was used for in situ monitoring of thin, microcrystalline diamond films deposited on silicon substrate in PA-CVD processes. The thickness of each film was measured by stylus profilometry and spectral reflectance analysis as a reference. The system setup and interferometric signal processing are also presented for evaluating the system parameters, i.e. measurement uncertainty, resolution and the range of measurable film thickness.
20
Content available remote Sintering of diamond composites with SHS-prepared bonding phases
EN
Purpose: The aim of this study was to investigate materials with reduced cobalt content as well as diamond compacts with non-cobalt bounding phase. Design/methodology/approach: Phases Ti3SiC2 and Cr3AlC obtained using the self-propagating High-Temperature Synthesis (SHS) technique were used as a PCD (polycrystalline diamond) bonding phases. Diamond composites with 10-20 mass% of SHS bonding phase were prepared by using a Bridgmann-type High Pressure - High Temperature (HP-HT) apparatus. Sintering of the composites were carried out at 1950±50°C and 8±0.2 GPa. Phase compositions of MAX powders and compacts were tested using X-ray diffraction. Microstructure investigations were performed using scanning (JEOL) and transmission (Tecnai FEG 200kV) microscopes and high spation resolution EDS mapping. Findings: During the sintering processes, bonding phase decomposition processes occur in the material. Mainly carbides and silicides are formed. Diamond phase materials are characterized by multi-phase composition. Research limitations/implications: Future research in the field of reduced cobalt content composites and cobalt replaced by bonding phase with Cr2AlC should focus on reduction of the graphite which affects on lower composite hardness. Such materials require an improvement in stress deposition. Originality/value: Due to the low thermal stability of the cobalt as a bonding phase in PCD there is a need to reduce its volume in the composite. Application of the newest non-cobalt bonding phases (Ti3SiC2 and Cr3AlC) obtained by SHS sythesis.
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