scholarly journals Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5531
Author(s):  
Edouard A. T. Davin ◽  
Anne-Lise Cristol ◽  
Arnaud Beaurain ◽  
Philippe Dufrénoy ◽  
Neomy Zaquen
Keyword(s):  
Heat Treatment ◽  
Gray Cast Iron ◽  
Organic Matrix ◽  
Third Body ◽  
Test Program ◽  
Brake Pads ◽  
The Matrix ◽  
Disc Configuration ◽  
Crack Faces ◽  
Reduced Scale

In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel (LS) formulation. The worn surfaces are observed with SEM. The toughness of the pad materials is tested at the raw state and after a heat treatment. During braking, the LS-GCI disc configuration produces heavy wear. The friction parts both keep their macroscopic integrity and wear appears to be homogeneous. The LS pad is mostly covered by a layer of solid oxidized steel. The NAO-GCI disc configuration wears dramatically and cannot reach the end of the test program. The NAO pad suffers many deep cracks. Compacted third body plateaus are scarce and the corresponding disc surface appears to be very heterogeneous. The pad materials both show similar strength at the raw state and similar weakening after heat treatment. However, the NAO material is much more brittle than the LS material in both states, which seems to favor the growth of cracks. The observations of crack faces suggest that long steel fibers in the LS material palliate the brittleness of the matrix, even after heat damage.

scholarly journals The Effect of Aging on Precipitates, Mechanical and Magnetic Properties of Fe-21Cr-15Ni-6Mn-Nb Low Magnetic Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 819
Author(s):  
Changsheng Li ◽  
Kun Li ◽  
Jingbo Dong ◽  
Jinyi Ren ◽  
Yanlei Song
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Magnetic Properties ◽  
Solution Heat Treatment ◽  
Aging Treatment ◽  
Relative Magnetic Permeability ◽  
Coarsening Behavior ◽  
The Matrix ◽  
Coherent Orientation

The effect of aging on the precipitates, mechanical and magnetic properties of Fe-21Cr-15Ni-6Mn-Nb low magnetic stainless steel were investigated. The steel was aged at 550–750 °C for 2 h after solution heat treatment at 1100 °C for 1 h. During the aging treatment, the (Nb, V)(C, N) particles gradually precipitated in the grain, which were coherent or semi-coherent with the matrix. When the aging temperature was beyond 650 °C, the coarsening rate of (Nb, V)(C, N) particles increase rapidly and the coherent orientation between (Nb, V)(C, N) particles and the matrix was lost gradually. Meanwhile, coarse M23C6 was distributed at the grain boundary with chain shape, which was non-coherent with the matrix. The coarsening behavior of (Nb, V)(C, N) precipitates in the grain was analyzed, and the size of the particles precipitated after aging treatment at 650°C for different time was calculated and studied. After aging treatment at 650 °C for 2 h, the yield strength and tensile strength of the stainless steel was 705.6 MPa and 1002.3 MPa, the elongation and the relative magnetic permeability was 37.8% and 1.0035, respectively.

Matrix-Mineral Relationships-A. Morphologist's Viewpoint

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 922-929 ◽  
Author(s):  
M.U. Nylen
Keyword(s):  
Organic Material ◽  
Crucial Role ◽  
Crystal Surface ◽  
Organic Matrix ◽  
The Other ◽  
Enamel Matrix ◽  
Initial Cell ◽  
Cell Product ◽  
Ultrastructural Morphology ◽  
The Matrix

The literature on the ultrastructural morphology of the enamel matrix and its relationship to the crystals is reviewed. Two morphological entities of the matrix are discussed: One is the so-called stippled material which may be the initial cell product; the other, variously described as fibrillar, lamellar, tubular or helical, is thought by many to play a crucial role in nucleation and orientation of the crystals. A number of observations, however, suggest that the latter structures form secondarily to the crystals and that in reality they represent organic material adsorbed to the crystal surface and maintained as independent structures upon removal of the mineral. The need for additional studies is stressed including systematic studies of interactions between constituents of the organic matrix and the apatite crystals.

Crystallization behavior, Al-Ce intermetallic formation, and microstructure refinement of near-eutectic Al–Si alloys by rare-earth element additions

2020 ◽  
Vol 111 (11) ◽  
pp. 938-952
Author(s):  
Bo Chi ◽  
Zhiming Shi ◽  
Cunquan Wang ◽  
Liming Wang ◽  
Hao Lian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Rare Earth ◽  
Rare Earth Element ◽  
Crystallization Behavior ◽  
Earth Element ◽  
Microstructural Refinement ◽  
Preferential Growth ◽  
Intermetallic Formation ◽  
The Matrix

Abstract Near-eutectic Al-Si alloys have low strength and high brittleness because of the presence of many eutectic b-Si flakes, needle-like Al-Fe-Si intermetallics, and coarse α-Al grains. This study disclosed the effects of cerium-rich RE (rare earth) element modification on orientation characters of crystals, formation of Al-Ce compounds, and microstructural refinement to improve the microstructure and mechanical properties of the alloys. The RE addition depressed preferential growth along the close-packed and/or sub-closepacked planes and promoted growth along the non-closepacked planes, in which La and other elements were dissolved into needle-like Al11Ce3 phase. When the temperature decreased, Al11Ce3 was preferentially crystallized from the melts and then devitrified by attaching to the surface of β-Al5FeSi needles. Moreover, many small Al11Ce3 particles were precipitated in the matrix and on the Si surface by a T6 heat treatment. Eutectic β-Si phases were constructed into discontinuous networks, short rods, and even particles by RE additions, which were further transformed into fine nodules following the T6 treatment. α-Al grains and primary β-Al5FeSi needles were simultaneously refined. The addition of 1.0 wt.% REs and subsequent T6 treatment yielded the highest tensile strength, elongation, and hardness of the alloy.

Application of Heat Treatment to Prevent Fracturing Fluid-Induced Formation Damage and Enhance Matrix Permeability in Shale Gas Reservoirs

2021 ◽  
Author(s):  
Mingjun Chen ◽  
Peisong Li ◽  
Yili Kang ◽  
Xinping Gao ◽  
Dongsheng Yang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hydraulic Fracturing ◽  
Shale Gas ◽  
Gas Transport ◽  
Formation Damage ◽  
Transport Capacity ◽  
Fracturing Fluid ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
The Matrix

Abstract The low flowback efficiency of fracturing fluid would severely increase water saturation in a near-fracture formation and limit gas transport capacity in the matrix of a shale gas reservoir. Formation heat treatment (FHT) is a state-of-the-art technology to prevent water blocking induced by fracturing fluid retention and accelerate gas desorption and diffusion in the matrix. A comprehensive understanding of its formation damage removal mechanisms and determination of production improvement is conducive to enhancing shale gas recovery. In this research, the FHT simulation experiment was launched to investigate the effect of FHT on gas transport capacity, the multi-field coupling model was established to determine the effective depth of FHT, and the numerical simulation model of the shale reservoir was established to analyze the feasibility of FHT. Experimental results show that the shale permeability and porosity were rising overall during the FHT, the L-1 permeability increased by 30- 40 times, the L-2 permeability increased by more than 100 times. The Langmuir pressure increased by 1.68 times and the Langmuir volume decreased by 26%, which means the methane desorption efficiency increased. Results of the simulation demonstrate that the FHT process can practically improve the effect of hydraulic fracturing and significantly increase the well production capacity. The stimulation mechanisms of the FHT include thermal stress cracking, organic matter structure changing, and aqueous phase removal. Furthermore, the special characteristics of the supercritical water such as the strong oxidation, can not be ignored, due to the FHT can assist the retained hydraulic fracturing fluid to reach the critical temperature and pressure of water and transform to the supercritical state. The FHT can not only alleviate the formation damage induced by the fracturing fluid, but also make good use of the retained fracturing fluid to enhance the permeability of a shale gas reservoir, which is an innovative method to dramatically enhance gas transport capacity in shale matrix.

Retrogression and Re-aging Heat Treatment: AA7XXX Aluminum Alloys

2019 ◽  
Author(s):  
V. Anil Kumar ◽  
S. Arjun ◽  
R.K. Gupta ◽  
P.V. Venkitakrishnan
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloys ◽  
Industrial Applications ◽  
Age Hardening ◽  
Large Cross Section ◽  
Structural Applications ◽  
The Matrix ◽  
Peak Aged ◽  
Aged Temper ◽  
Short Time

Retrogression and re-aging (RRA) treatment was introduced to increase the stress corrosion cracking (SCC) resistance while retaining the strength attainable in T6 (peak aged) temper. Retrogression is a short-term heat treatment at an elevated temperature wherein a partial dissolution of metastable precipitates occurs, which are responsible for the hardening. During the next step, the material is re-aged in the regime of typical age hardening parameters to restore the strength with improved ductility. Response of RRA treatment has been reported on AA7XXX series Aluminum alloys such as AA7075, AA7050, AA7150, AA7049, and AA7010. Studies have been done on the effect of RRA on microstructure, mechanical properties such as tensile and hardness, corrosion, exfoliation corrosion, and SCC resistance by various researchers. The key characteristic of RRA is retrogression, which makes the re-precipitation in the matrix and coarsening of grain boundary precipitates such as MgZn2, η′. The retrogression treatment however requires high temperature and a short time, which limits the industrial application of RRA, especially in the heat treatment of the components with large cross section, due to the inherent thermal conductivity limitations. Hence, further work needs to be done in this area to apply this specialized heat treatment for industrial applications. This article brings out a comprehension of the changes in microstructure, tensile properties, and corrosion resistance of the various commonly used AA7XXX Aluminum alloys in structural applications with RRA heat treatment. The future scope of the work in RRA heat treatment is also discussed in this article.

scholarly journals Влияние режима получения образцов и термообработки на локальную структуру халькогенидного полупроводника Ge-=SUB=-2-=/SUB=-Sb-=SUB=-2-=/SUB=-Te-=SUB=-5-=/SUB=-

2022 ◽  
Vol 56 (3) ◽  
pp. 291
Author(s):  
С.Н. Гарибова ◽  
А.И. Исаев ◽  
С.И. Мехтиева ◽  
С.У. Атаева ◽  
Р.И. Алекперов
Keyword(s):  
Heat Treatment ◽  
Thermal Processing ◽  
Thermal Evaporation ◽  
Amorphous State ◽  
Hexagonal Structure ◽  
Structural Elements ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Close Range

Specifics of "amorphous state - crystal" phase transitions in dependence on the samples obtaining method and thermal processing, as well as changes in the structure and close range order in the arrangement of the atoms of Ge20Sb20.5Te51 chalcogenide semiconductors have been studied by the x-ray diffraction and Raman spectroscopy. It has been shown that Ge20Sb20.5Te51 films obtained by thermal evaporation on an unheated substrate are amorphous; after heat treatment at 220 and 400 °C, transform into a crystalline phase with a cubic and hexagonal structure. The chemical bonds and the main structural elements that form the matrix of the investigated objects, as well as the changes that occur in them during heat treatment, have been determined.

Effect of Heat-Treatment Time on Microstructure and Mechanical Properties of Mg-5Gd-2Y-2Zn-0.5Zr Alloy

2012 ◽  
Vol 482-484 ◽  
pp. 1384-1389 ◽  
Author(s):  
Ling Gang Meng ◽  
Can Feng Fang ◽  
Peng Peng ◽  
Nai Pu Li ◽  
Qiong Zhu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Treatment Time ◽  
Time Range ◽  
Lpso Phase ◽  
High Temperature Heat Treatment ◽  
Lpso Structure ◽  
The Matrix ◽  
New Type ◽  
The Stability

Microstructure evolution of Mg-5Gd-2Y-2Zn-0.5Zr alloy during high temperature heat-treatment at 500°C in the time range 10-70h was investigated. The results show that after adding the element Y, the as-cast Mg-5Gd-2Y-2Zn-0.5Zr alloy forms the Mg12Zn(Y,Gd) phase with 18R-LPSO structure at the grain boundary. During heat-treatment at 500°C, the stability of 18R-LPSO structure is weakened by Gd atoms, parts of LPSO phases dissolve gradually into the matrix with time prolonged and a new type Mg(Y,Gd)Zn phase come into being. LPSO phase in the grain boundary can ensure the ultimate tensile strength and elongation of the alloy, and effect of dissevering on the LPSO phase by Mg(Gd,Y)Zn phase results the decrease of UTS and elongation.

Effect of Heat Treatment on the Structure and Properties of EW75 Magnesium Alloy Plate

2013 ◽  
Vol 747-748 ◽  
pp. 158-165
Author(s):  
Juan Qu ◽  
Kui Zhang ◽  
Ming Long Ma ◽  
Yong Jun Li ◽  
Xing Gang Li
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Tensile Strength ◽  
Solution Process ◽  
Solution Time ◽  
Solution Temperature ◽  
Second Phase ◽  
Alloy Plate ◽  
T6 Heat Treatment ◽  
The Matrix

In this study, Mg-7Gd-5Y-1Nd-0.5Zr alloy (EW75) was produced by melting method and then press-forged into large size plate. The properties of the Mg-7Gd-5Y-1.2Nd-0.5Zr alloy were optimized through T6 heat treatment. The microstructures of alloy were observed by means of optical microscopy (OM), scanning electron microscopy (SEM). Its mechanical properties under different heat treatment conditions were determined by tensile tests. The results indicated that increasing the solid solution temperature and prolonging the solid solution time can both lead to the dissolution of second phase in the alloy back into the matrix. The solid solution temperature affects the dissolution process more than the solid solution time. Grain growth occurred during the solid solution process. The grain size of the matrix enlarges with the increase of solid solution temperature. The tensile test result showed that the tensile strength of the alloy was significantly improved after T6 heat treatment. Its tensile strength in the same direction was nearly 40% up after T6 heat treatment. The analysis shows that T6 heat treatment can effectively eliminate the larger deformed precipitates and beneficial to the formation of hard precipitates, which leads to an improvement in the alloys tensile strength.

Effect of the matrix resin structure on the mechanical properties and braking performance of organic brake pads

2012 ◽  
Vol 126 (5) ◽  
pp. 1746-1753 ◽  
Author(s):  
Hai-Qing Wang ◽  
Xing-Yang Wu ◽  
Tong-Sheng Li ◽  
Xu-Jun Liu ◽  
Pei-Hong Cong
Keyword(s):  
Mechanical Properties ◽  
Matrix Resin ◽  
Braking Performance ◽  
Brake Pads ◽  
The Matrix

METAL COMPOSITE MATERIALS BASED ON TITANIUM ALLOYS, REINFORCED WITH REFRACTORY PARTICLES (review)

2021 ◽  
pp. 36-45
Author(s):  
E.I. Krasnov ◽  
◽  
V.M. Serpova ◽  
L.G. Khodykin ◽  
A.V. Gololobov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Composite Materials ◽  
Literature Review ◽  
Titanium Alloys ◽  
Chemical Nature ◽  
Physical And Mechanical Properties ◽  
Metal Composite ◽  
The Matrix ◽  
Metal Composite Materials

Presents a literature review in the field of methods for strengthening titanium and its alloys by introducing various refractory particles into the matrix. The main problematic issues related to the chemical nature of refractory particles and titanium alloys that arise during hardening are briefly described. The main structural, physical and mechanical properties and morphology of such metal composite materials are described. The dependence of the influence of various refractory particles and their amount, as well as the effect of heat treatment on the physical and mechanical properties of microns based on titanium alloys, is presented.

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