Study of the Abrasion Resistance of Fe-Cu-Nb and NEXT 100® Metallic Matrices for the Manufacture of Diamond Tools

2018 ◽  
Vol 930 ◽  
pp. 395-399
Author(s):  
Hellen C.P. de Oliveira ◽  
Adriano Corrêa Batista ◽  
Genivaldo Júlio Perpétuo ◽  
Thales Eduardo Leal ◽  
Ana Carolina Fernandes Reis ◽  
...  

The substitution of cobalt, present in the commercial binder metal matrix commonly used by the industry, was analyzed: 25,2%Fe-49,5%Cu-24,1%Co – NEXT 100® by the niobium element of the Fe-Cu-Co system, obtaining 4 metal matrices: 28,34%Fe–56,66%Cu–15%Nb; 25%Fe–50%Cu–25%Nb; 21,67%Fe–43,33%C–35%Nb; 18,34%Fe–36,66%Cu–45%Nb. This study aims to evaluate the behavior of metal matrices to better choose the type of matrix to be used in the manufacture of diamond tools. The metal powders were blended according to the compositions of each metal matrix and then hot pressed at 800o /35MPa / 3min, thus occurring the sintering. The sintered samples of each metal matrix were conducted to the Abrasion Resistance test in order to verify the wear, for the accumulated times of 2, 6, 12 and 20 minutes. In these metal matrices, density, porosity and Vickers hardness (HV5) tests were performed to better understand the wear suffered by the samples. Thus, the metal matrix 25% Fe-50%Cu-25%Nb presented, in the general context of the properties and from the abrasive point of view, satisfactory results capable of replacing the NEXT 100 matrix.

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1010
Author(s):  
Zachary S. Levin ◽  
Michael J. Demkowicz ◽  
Karl T. Hartwig

We investigated the effectiveness of severe plastic deformation by equal channel angular extrusion (ECAE) for consolidation of metal powders into metal matrix composites. Equal volumes of copper (Cu) and tantalum (Ta) powders were consolidated at ambient temperature via different ECAE routes. Composites processed by ECAE routes 4E and 4Bc were also processed at 300 °C. The resulting materials were characterized by scanning electron microscopy (SEM) and compression testing. Processing by route 4Bc at 300 °C resulted in the highest compressive strength, lowest anisotropy, and least strain rate sensitivity. We conclude that the superior properties achieved by this route arise from mechanical bonding due to interlocking Cu and Ta phases as well as enhanced metallurgical bonds from contact of pristine metal surfaces when the material is sheared along orthogonal planes.


Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1774
Author(s):  
Elżbieta Cygan-Bączek ◽  
Piotr Wyżga ◽  
Sławomir Cygan ◽  
Piotr Bała ◽  
Andrzej Romański

The work presents the possibility of fabricating materials for use as a matrix in sintered metallic-diamond tools with increased mechanical properties and abrasion wear resistance. In this study, the effect of micro-sized SiC, Al2O3, and ZrO2 additives on the wear behaviour of dispersion-strengthened metal-matrix composites was investigated. The development of metal-matrix composites (based on Fe–Mn–Cu–Sn–C) reinforced with micro-sized particles is a new approach to the substitution of critical raw materials commonly used for the matrix in sintered diamond-impregnated tools used for the machining of abrasive stone and concrete. The composites were prepared using spark plasma sintering (SPS). Apparent density, microstructural features, phase composition, Young’s modulus, hardness, and abrasion wear resistance were determined. An increase in the hardness and wear resistance of the dispersion-strengthened composites as compared to the base material (Fe–Mn–Cu–Sn–C) and the commercial alloy Co-20% WC provides metallic-diamond tools with high-performance properties.


1949 ◽  
Vol 22 (3) ◽  
pp. 838-862 ◽  
Author(s):  
T. R. Griffith ◽  
E. B. Storey ◽  
J. W. D. Barkley ◽  
F. M. McGilvray

Abstract In development work on GR-S commercial recapping compounds originated in 1943 by the Directorate of Mechanical Engineering, Department of National Defence, Ottawa, Canada, in which an attempt was made to correlate road performance with physical properties as determined in the laboratory, it was found that no relationship whatever existed between the results of road tests carried out under the supervision of that directorate and standard laboratory abrasion resistance tests carried out in the Canadian National Research Council Rubber Laboratory at Ottawa. In the laboratory test the sandpaper in the abrasion machine became coated with a smear of tacky viscous material which the air jet was unable to remove. Under these conditions the rubber tends to slide over the sandpaper surface, with relatively little actual abrasion of the rubber. The effect remains even after a considerable overcure of the sample. It was felt that the removal of the tacky viscous material from vulcanized GR-S by extraction might give more reliable abrasion resistance results, inasmuch as, on the road, rubber is constantly coming in contact with a new surface and such viscous material is thus being continually removed as it migrates to the surface of the rubber. From this point of view, then, the tread surface while being abraded on the road may be looked upon as extracted rubber and may be considered as conforming closely to the extracted laboratory specimen.


2018 ◽  
Vol 4 (s1) ◽  
pp. s146-s171
Author(s):  
Michał Mrugalski

AbstractConsidering that enacitivsm emerged in rebellion against the representativism of first-generation cognitive science, an enactivist approach to narrative, which after all does relate events, situations, people, necessitates a directly realistic (i. e. anti-representationalist) concept of perspective on literary objects. Ingarden’s description of the spatio-temporal properties of the cognizing of the literary work, in the process of which the reader transgresses the realm of signs (representation) toward embodied and culturally embedded cognition of objects and events in a presented world, may serve as a prototype for an enactive approach narrative, provided the theory in question is situated in its original context, for example that of Ingarden’s ongoing discussion with structuralism regarded at this juncture as a representationist stance. In the first step, I am referring to the philosophical tradition of direct realism, which was apparently invigorated by the theories of embodied and enactive cognition, to propose a way of conceiving first-person perspective on literary objects and events, first-person and temporal perspective on objects being the royal road to all sorts of enaction. In the second step, I am tackling the issue of point of view in East and Central European structuralism by recalling its most general context of the dialectical relationship between synchrony and diachrony. The interpretation of linguistic signs by the receiver is a space in which structuralism and Ingarden’s phenomenology concur as they share a similar model of receptive temporality, rooted in Husserl’s description of the inner consciousness of time and aiming to reduce the ambiguity of linguistic units and increase the predictability of meaning. In Ingarden, however, there is a threshold between the linguistic and the extralinguistic elements of the literary work, which are conceived in a directly realistic manner. I specifically recall the notion of “objectification,” which was suppressed by that of “concretization,” as a borderland between indirect (semiotic) and indirect (objectual and enactive) representation. In the conclusion, I point to the major differences between present-day cognitivist aesthetics and Ingarden’s approach, which was immersed in the culture of his time, and ask whether these differences impede us to achieve as interesting results as Ingarden’s.


2019 ◽  
Vol 16 (16) ◽  
pp. 158-169
Author(s):  
Olena Stanishevska

Introduction. In scientific literature dedicated to J. Brahms, much attention has been paid to a song genre. The researches note that J. Brahms’s songs can be regarded as a continuation of genre-specific features of Austro-German Lied, which retains the purity of the generic semantics in the composer’s works, without involving typically operatic means of vocal intoning, or approaching the so-called “poem with music”. J. Brahms’s songs do not allow the singer to demonstrate the full range of his/her voice, to reveal his/her artistic temperament, to show the technical skill. Absorption in a special emotional aura of J. Brahms’s songs requires a variety of timbre-intonational resources of a singer, his/her ability not to lose the sense of the whole while detailing the melodious overture. Of particular interest is the issue of music and words correlation in J. Brahms’s songs. As a rule, the composer is considered to be the immediate successor of F. Schubert rather than R. Schuman in his orientation to musical embodiment of a generalized poetic image. At the same time, this issue requires more detailed study, since the composer was very sensitive to the poetic text, in particular, from the point of view of coordinating the intonation-phonetic features of German language and vocal intonation. Theoretical Background. Recent research and publications analysis. Opus 49 by J. Brahms seems to be in the shadow of musicological thought and performing practice. It should be noted that a very famous opus part is “Lullaby”, which is mentioned in the monographs of K. Tsareva (1986), M. Druskin (1959), and K. Geiringer (1965). In the literature being considered the abovementioned opus is not completely covered, thus determining the relevance of our article. There are references to individual songs in different sources, but incidentally, in the context of different issues. Objective is to study J. Brahms’s opus 49 in the aspect of the interaction of poetic word and music, verbal and musical intoning. Methods: 1) historical method, allowing to comprehend the selected material in the perspective of the development of Austro-German song of the XIX century; 2) intonational method, which involves the study of vocal melody in terms of phonetic-tonic links; 3) genre method, caused by the features of chamber vocal lyrics; 4) stylistic method, corresponding to a specific opus consideration in the general context of the composer’s creative work. Results and Discussion. The composer did not have any tendency to the songs cyclization, however, the vocal miniatures, assembled in one opus, appear to be lyrical notes, self-contained but united by poetic motives and nature of the author’s expression. Many researchers see a cyclic organization of his particular vocal opuses. For example, I. Mykhailov (1987: 19) proves the existence of cyclic principles at different compositional levels in composer’s songs: separate “melodious pairs”, a number of songs with the texts by one poet inside the opus, a whole vocal opus with the texts by different authors. According to I. Mikhailov, the cyclic connection of songs is emphasized by several compositional techniques: thematic one, i.e. the unity of the musical material; the continuity of songs alternation, which is sometimes manifested in the absence of a piano introduction of the next song. In opus 49, the author chooses different poetic sources – poems by P. Heyse, L. Hölty, A. F. Schack, and J. Wenzig. The composer refers to one of the samples of the famous collection by Joachim von Arnim and Clemens Brentano “The Magic Horn of a Boy”. Given the anthological principle of poetic texts selection, no transparent storyline in opus 49, such as “A Beautiful Miller” by F. Schubert or “Poet’s Love” by R. Schumann, there is no reason to regard it as a cycle. However, the opus’ songs are arranged in a certain semantic sequence. Owing to the fact that three songs (“Sunday Morning”, “To a Violet”, “Longing for the Sweetheart”) are united by homogeneous poetic motifs, one can regard them as forming a microcycle within the whole. The second micro-cycle of the opus is represented by No. 4 and No. 5 (“Lullaby” and “Twilight”). In interpreting the poetic text, J. Brahms adheres to the principle of emotional and musical generality, once detailing the text, if at all. Here, he succeeds F. Schubert. However, he uses the technique of keywords, distinguishing them in two ways: rhythmically (with syncope) and through intrinsic chants; the composer also uses different types of intoning. Following the tradition of the 19th-century Austro-German song, the composer regards the genre as an alliance of two full members: the vocalist and the pianist, with the part being an instrumental generalization. The intonational image of the whole in vocal music arises at the crossing of two texts – poetic and musical. German has intonation difficulties owing to a large number of consonants. Problems, encountered by the singers in intoning German language, are compensated by the consonants and vowels, which are most favorable for correct sound formation, allowing to achieve the required quality. The soft consonants and vowels should be regarded as the ideal vocal sound, that is, a model for other phonemes in musical-poetic text. While creating vocal melodies of Opus 49 songs, J. Brahms cares the phonetics of a German text in the singing to be comfortable for the performer. Conclusions. J. Brahms uses such principles and techniques of literary original musical embodiment as preservation of the holistic image, created by the author of the poems, on the one hand, and its detailing on the other. In the second case, the composer resorts to all means of musical expression: motive-thematic, texture-register, rhythmic, harmonious, texture ones. The prospects of the research lie in studying the interaction of verbal and musical intonation in other vocal works of J. Brahms, as well as in chamber-vocal music of late romantics.


Mathematics ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 1231
Author(s):  
Carmen Escribano ◽  
Raquel Gonzalo ◽  
Emilio Torrano

In this work, our aim is to obtain conditions to assure polynomial approximation in Hilbert spaces L 2 ( μ ) , with μ a compactly supported measure in the complex plane, in terms of properties of the associated moment matrix with the measure μ . To do it, in the more general context of Hermitian positive semidefinite matrices, we introduce two indexes, γ ( M ) and λ ( M ) , associated with different optimization problems concerning theses matrices. Our main result is a characterization of density of polynomials in the case of measures supported on Jordan curves with non-empty interior using the index γ and other specific index related to it. Moreover, we provide a new point of view of bounded point evaluations associated with a measure in terms of the index γ that will allow us to give an alternative proof of Thomson’s theorem, by using these matrix indexes. We point out that our techniques are based in matrix algebra tools in the framework of Hermitian positive definite matrices and in the computation of certain indexes related to some optimization problems for infinite matrices.


2018 ◽  
Vol 274 ◽  
pp. 1-8 ◽  
Author(s):  
I. Iparraguirre ◽  
L. Lozada ◽  
F. Ibarreta ◽  
R. Martinez ◽  
J.M. Sanchez

TiC-WC-(Ni,Co,Cr) cermets are potential candidates for the substitution of straight cemented carbides in certain wear applications. This work analyses the effect of Ti/W and Co/Ni ratios on the microstructure and abrasion resistance of this type of cermets. From a microstructural point of view, cermets in the (Ti,W)C-(Ni,Co,Cr) pseudo-binary region show uncontrolled (Ti,W)C grain growth and a high degree of contiguity of the carbide phase. A microstructural refinement is observed as the Ti/W ratio decreases, especially when WC precipitation occurs. Abrasion resistance in these materials is dominated by hardness.


Author(s):  
Naseem Ahamad ◽  
Aas Mohammad ◽  
Kishor Kumar Sadasivuni ◽  
Pallav Gupta

The aim of the present work is to investigate vickers hardness, wear behavior as well as to perform optimization of wear data for pure Al and Al-Al2O3-TiO2 hybrid metal matrix composites. The hybrid composite (Al-Al2O3-TiO2) was prepared by mechanical stir casting with equal proportion of reinforcement (2.5, 5.0, 7.5 and 10 wt.%). Vickers hardness, wear behavior and its optimization using ANOVA as well as TOPSIS along with the microstructure of the worn surface of prepared sample has been investigated. Vickers hardness increases with an increase in weight percentage of reinforcements. Wear test was carried out under dry sliding condition by pin-on-disc wear machine according to the ASTM G99-95a standard. Wear properties of the sample have been obtained at different percentages of reinforcement. Wear resistance of the hybrid composite increases with the variation of percentage of titanium oxide particles due to its lubricating properties. ANOVA shows that the reinforcements and load have different effect on samples wear rate. TOPSIS analysis shows rank of the sample according to its wear rate. Worn surface morphology was investigated and it showed deep grooves, more debris, delamination and rough surface in pure Al sample as compared to the high percentage of reinforced hybrid metal matrix composites.


1993 ◽  
Vol 08 (11) ◽  
pp. 1047-1061 ◽  
Author(s):  
S. KHARCHEV ◽  
A. MARSHAKOV ◽  
A. MIRONOV ◽  
A. MOROZOV

We consider the deformations of "monomial solutions" to generalized Kontsevich. model1,2 and establish the relation between the flows generated by these deformations with those of N = 2 Landau-Ginzburg topological theories. We prove that the partition function of a generic generalized Kontsevich model can be presented as a product of some "quasiclassical" factor and non-deformed partition function which depends only on the sum of Miwa transformed and flat times. This result is important for the restoration of explicit p − q symmetry in the interpolation pattern between all the (p, q)-minimal string models with c < 1 and for revealing its integrable structure in p-direction, determined by deformations of the potential. It also implies the way in which supersymmetric LandauGinzburg models are embedded into the general context of GKM. From the point of view of integrable theory these deformations present a particular case of what is called equivalent hierarchies.


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