The Effect of Heating on Phase Composition of the Cr3C2- Ti System Hard Alloys Fabricated by the Explosive Compaction of Powder Mixtures

2019 ◽  
Vol 945 ◽  
pp. 617-622 ◽  
Author(s):  
V.O. Kharlamov ◽  
Aleksandr Vasilevich Krokhalev ◽  
S.V. Kuz’min ◽  
V.I. Lysak
Keyword(s):  
Phase Composition ◽  
Chromium Carbide ◽  
Heating Temperature ◽  
Calculated Data ◽  
Fine Powder ◽  
Hard Alloys ◽  
Explosive Compaction ◽  
X Ray ◽  
Diffusion Layers ◽  
Equilibrium Phases

The article reports findings on theoretically-calculated data and experimental results obtained with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy methods of the analysis of hard alloys produced by the explosive compaction of the Cr3C2 chromium carbide powders with titanium, first in the original condition and then after heating to 1200 °C. It was established that when heated to 600 °С the phase composition of hard alloys does not change and corresponds to the composition of the original components of the powder mixture. When the heating temperature was increased to 650 °С, new fine powder fractions emerged at the “chromium carbide – titanium” interface. At the temperature of 700 °С two separate diffusion layers emerged and grew in the opposite directions. Due to this growth the source phases in the alloy fully disappeared at 1200 °С and two equilibrium phases were formed.

Investigation of the Structure and Distribution of Chemical Elements between the Phases of Hard Alloys of the Cr3C2-Ti System, Obtained at Various Modes of Explosive Compaction

2020 ◽  
Vol 992 ◽  
pp. 487-492
Author(s):  
V.O. Kharlamov ◽  
Aleksandr Vasilevich Krokhalev ◽  
S.V. Kuz’min ◽  
V.I. Lysak
Keyword(s):  
Phase Composition ◽  
Powder Mixture ◽  
Chemical Interaction ◽  
Chemical Elements ◽  
Equilibrium Phase ◽  
Hard Alloys ◽  
Explosive Compaction ◽  
Thermo Calc Software ◽  
Equilibrium Phases ◽  
Explosive Pressing

The Article presents the findings of the studies of the microstructure, chemical and phase composition of the Cr3C2-Ti system alloys obtained by the explosion. Scanning electron microscopy, energy dispersive and x-ray diffraction analyses were used. The program Thermo-Calc software was used to calculate the equilibrium phases. The phase composition of the compact was shown to fully correspond to that of the initial powder mixture during explosive pressing in the modes of heating from 300 ̊С to 600 ̊С. When heated above 600 ̊С, the chemical interaction of the initial components begins with the formation of new boundary phases. Meanwhile, there is a change in the sample destruction nature and a significant increase in hardness, which points to the hard alloy consolidation. The increase in the powder mixture heating in shock waves to 1000 ̊С leads to intensive macrochemical interaction of the powder mixture components and to formation of an equilibrium phase composition. The established temperature limits determine the most appropriate parameters of shock-wave loading when producing hard alloys by explosive pressing.

FUNDAMENTALS OF WEAR-RESISTANT COATING PRODUCTION FROM CHROMIUM CARBIDE POWDER MIXTURE WITH BINDER METAL BY EXPLOSIVE COMPACTION

2018 ◽  
pp. 68-83
Author(s):  
A. V. Krokhalev ◽  
V. O. Kharlamov ◽  
S. V. Kuzmin ◽  
V. I. Lysak
Keyword(s):  
Chromium Carbide ◽  
Elevated Temperatures ◽  
Heating Temperature ◽  
Carbide Powder ◽  
Hard Alloys ◽  
Compression Pressure ◽  
Explosive Compaction ◽  
Powder Mixtures ◽  
Wear Resistant ◽  
Wide Range

The article presents experimental data on explosive compaction of chromium carbide (Cr3C2) powder mixtures with metals (Ti, Ni, Cu) provided with theoretical explanations. These data were used as a basis for stating science-based principles of composition selection and technology development to produce antifriction wear-resistant chromium carbide hard alloys and coatings by explosion. Explosive compaction of powder mixtures was carried out according to a scheme using a normally incident plane detonation wave in a wide range of loading parameters (powder heating temperature in shock waves varied from 200 to1000 °Cand maximum shock compression pressure varied from 4 to 16 GPa during experiments). Phase transformation analysis was carried out by the numerical thermodynamic modeling of phase equilibrium using the Thermo-Calc software. Microstructure, chemical and phase compositions were studied using optical («Axiovert 40МАТ» by CarlZeiss,Germany), scanning («Versa 3D» and «Quanta 3D FEG» byFEI,USA), transmission («BS 540» byTesla,Czech Republic, «Titan 80-300» and «Tecnai G2 20F» byFEI,USA) electron microscopes and «Solver Pro» atomic force microscope (LLC «NT-MDT», Zelenograd). Temperature stability and oxidation resistance at elevated temperatures of the materials obtained by explosion was studied using thermogravimetric analysis (TGA) using the «STA 449 F3 Jupiter» instrument (NETZSCH, Germany) in the synthetic air environment when heated to1500 °C. Tribological tests were carried out on the MI-1M friction machine (MEZIMiV,Moscow) according to the pin-on-ring scheme with plunging in distilled water environment. The mechanisms of consolidation and formation of strong boundaries between powder material particles during explosive compaction are described. It is shown that hard alloys of chromium carbide with titanium bond obtained by explosion retain their phase compositions without any changes and resist to oxidation up to600 °C, and also have significantly better anti-friction properties and wear resistance than the SGP-0,5 and KHN-20 materials used in water-lubricated friction couples until the present time.

scholarly journals Influence of the nano-WC content and Sintering Temperature on the Phase Composition of Hard Alloys in the System TiC–WC–VC–NiCr

2020 ◽  
Vol 21 (3) ◽  
pp. 496-502
Author(s):  
S. Pukas ◽  
L. Zinko ◽  
N. German ◽  
R. Gladyshevskii ◽  
I. V. Koval ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Composition ◽  
Phase Analysis ◽  
Sintering Temperature ◽  
Technological Factor ◽  
Hard Alloys ◽  
X Ray ◽  
Metal Binder

The effect of the WC content and the sintering temperature, as the main technological factor, on the phase composition of TiC–xWC–5VC–18NiCr alloys was investigated by X-ray phase analysis. It was established that the main phases in the investigated alloys were the NaCl-type quaternary (Ti,V,W)C phase and a solid solution of Cr in Ni. Depending on the size of the WC particles used for the preparation, the metal binder could be described by the formula Ni0.75Cr0.25 (for nano WC) or Ni0.5Cr0.5 (for fine-sized WC). In alloys prepared with fine-sized WC, elementary Cr and traces of the Cr3C2 and Cr23C6 were also found. With increasing content of nano-sized WC and sintering temperature the solubility of W in (Ti,V)C increased. No W2C phase was detected under the conditions of the investigation.

Formation of Hard Alloys of Chromium Carbide and Titanium Powder Mixtures by Explosive Pressing

2016 ◽  
Vol 684 ◽  
pp. 193-197
Author(s):  
V.O. Kharlamov ◽  
Aleksandr Vasilevich Krokhalev ◽  
S.V. Kuz’min ◽  
V.I. Lysak
Keyword(s):  
Chromium Carbide ◽  
Electron Probe ◽  
Titanium Powder ◽  
Hard Alloys ◽  
High Melting ◽  
Explosive Compaction ◽  
Powder Mixtures ◽  
New Type ◽  
Scanning Electron ◽  
Explosive Pressing

The production of a new type of hard alloys by explosive compaction of chromium carbide (Cr3C2) and titanium powder mixtures was investigated. The phase composition of the fabricated alloys was studied using scanning electron probe microanalysis. The chemical composition of the alloy components does not change, and no redistribution of the elements was observed. The formation characteristics of the interfaces between the material components during shock wave processing were investigated using electron microscopy. The explosion compaction of high melting carbide and metal powder mixtures results in the formation of consolidated hard alloys during the compaction stage.

Determination of the phase composition of partially dehydroxylated kaolinites by modelling their X-ray diffraction patterns

Clay Minerals ◽  
2019 ◽  
Vol 54 (3) ◽  
pp. 309-322
Author(s):  
Victor A. Drits ◽  
Boris A. Sakharov ◽  
Olga V. Dorzhieva ◽  
Bella B. Zviagina ◽  
Holger Lindgreen
Keyword(s):  
Phase Composition ◽  
Heating Temperature ◽  
Full Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weight Losses ◽  
Diffraction Patterns ◽  
Xrd Patterns ◽  
Three Phases

AbstractModelling of experimental X-ray diffraction (XRD) patterns is used to determine the phase composition of partially dehydroxylated kaolinite samples. To identify unambiguously the presence of two or three phases in the heated kaolinite samples, the full range of their XRD patterns has to be analysed. Two different kaolinites, from Imerys (UK) and from Georgia (USA; KGa-21), were studied. The heating temperatures were selected to cover the entire range of dehydroxylation for both kaolinites (400–550°C for Imerys and 400–495°C for KGa-21). Two different dehydroxylation pathways were observed. At each stage of partial dehydroxylation, the kaolinite from Imerys consisted of the original, non-dehydroxylated kaolinite and of a fully dehydroxylated phase, metakaolinite. During partial dehydroxylation of kaolinite KGa-21, each product formed at a given heating temperature consisted of three phases: the original kaolinite; a dehydroxylated phase, metakaolinite; and a phase with diffraction features corresponding to a defective kaolinite-like structure. To determine the content of metakaolinite in a partially dehydroxylated specimen, its experimental XRD pattern was reproduced by the optimal summation of the diffraction patterns of the initial kaolinite and metakaolinite. A procedure that reveals the basic diffraction features of the third phase is suggested. The XRD patterns and thus the structures of the metakaolinites formed after dehydroxylation of the Imerys and KGa-21 samples differ substantially. The conventional determination of the initial kaolinite and metakaolinite contents in partially dehydroxylated kaolinite based on the analysis of basal reflections and weight losses may lead to overlooking the formation of the intermediate phases.

The Feasibility of Usage TiN and CrN Barrier Sublayers for Improving the Adhesion of Polycrystalline Diamond Films on WC-Co Hard Alloys

2016 ◽  
Vol 685 ◽  
pp. 583-586
Author(s):  
Stepan A. Linnik ◽  
Alexander V. Gaydaychuk ◽  
Eugene Y. Barishnikov
Keyword(s):  
Phase Composition ◽  
Glow Discharge ◽  
Magnetron Sputtering ◽  
Small Angle ◽  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Chromium Nitride ◽  
Hard Alloys ◽  
X Ray Diffraction ◽  
X Ray

In the present study, the influence of Chromium nitride (CrN) and Titanium nitride (TiN) sublayers on the adhesion of polycrystalline diamond films applied to WC-Co substrates was investigated. CrN and TiN layers were deposited on WC-Co substrates by magnetron sputtering in Ar/N2 atmosphere. Synthesis of diamond films was conducted in an AC abnormal glow discharge CVD reactor. The phase composition of the films was characterized by small-angle X-ray diffraction (XRD). The adhesion of diamond films was compared by analysis of Rockwell indentation imprints. It was found that TiN does not react with the carbon of the diamond film while CrN almost completely converted into chromium carbide (Cr3C2). Adhesion tests showed that the efficiency of these sublayers usage is substantially lower than using a Murakami and HNO3/H2O pretreatment.

X-ray diffraction layer-by-layer analysis of tungsten carbide-based hard alloys

2020 ◽  
Vol 86 (8) ◽  
pp. 38-42
Author(s):  
K. E. Smetanina ◽  
P. V. Andreev ◽  
E. A. Lantsev ◽  
M. M. Vostokov ◽  
N. V. Malekhonova
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Spark Plasma Sintering ◽  
Physical And Mechanical Properties ◽  
Hard Alloys ◽  
Layer By Layer ◽  
X Ray ◽  
Novel Technologies ◽  
Plasma Sintering ◽  
Spark Plasma

Improvement of the physical and mechanical properties of hard alloys based on WC – Co widely used in manufacturing of structural and tool products nowadays results from the use of novel technologies providing formation of a homogeneous high-density structures. Slight deviations of the carbon content from the equilibrium state lead to the formation of brittle η-phases (in particular, Co3W3C) and, accordingly, to deterioration of the mechanical properties of the product. We present the results of studying the homogeneity of the phase composition of the samples of hard alloys WC + 10% Co, obtained using advanced technologies of plasma-chemical synthesis and spark plasma sintering (SPS). The layer-by-layer X-ray phase analysis revealed the heterogeneity of the phase composition in depth: the brittle η-phase (Co3W3C) appears at a depth of ≥100 μm and reaches a constant value of 18 ± 1 wt.% at >200 μm, which indirectly confirms the hypothesis of carbon diffusion from graphite punches contacting with the surface of sintered samples and makes it possible to expand the range of parameters affecting the process of spark plasma sintering.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Formation of nanoscale sodium dodecahydro-closo- dodecaborate Na2[B12H12] on silicate matrix surface

2019 ◽  
Vol 484 (1) ◽  
pp. 41-43
Author(s):  
E. A. Malinina ◽  
V. K. Skachkova ◽  
I. V. Kozerozhets ◽  
V. V. Avdeeva ◽  
L. V. Goeva ◽  
...  
Keyword(s):  
Phase Composition ◽  
Ammonium Salt ◽  
Liquid Glass ◽  
Silicate Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Salt Sample ◽  
Matrix Surface

The method of nanoscaled sodium dodecahydro-closo-dodecaborate Na2[B12H12] synthesis is presented. The composite is heated to 200°C to yield the desired product, forming with the introduction of triethyl- ammonium salt [Et3NH]2[B12H12] into the silicate matrix of a sodium liquid glass. The morphology and phase composition of the synthesized sample are studied through SEM and X-ray diffraction methods, in comparison to those of a standard salt sample Na2[B12H12]. Based on the obtained data, the sample under study is an amorphous composite, on the surface of which nanoscale crystals of Na2[B12H12] form.

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