Physical and mechanical properties of Strain-Hardening Cement-based Composites (SHCC) after exposure to elevated temperatures

2009 ◽  
pp. 217-222
Alloy Digest ◽  
1983 ◽  
Vol 32 (3) ◽  

Abstract BRUSH Alloy 3 offers the highest electrical and thermal conductivity of any beryllium-copper alloy. It possesses an excellent combination of moderate strength, good corrosion resistance and good resistance to moderately elevated temperatures. Because of its unique physical and mechanical properties, Brush Alloy 3 finds widespread use in welding applications (RWMA Class 3), current-carrying springs, switch and instrument parts and similar components. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, joining, and surface treatment. Filing Code: Cu-454. Producer or source: Brush Wellman Inc..


2018 ◽  
Vol 7 (4.20) ◽  
pp. 205 ◽  
Author(s):  
Aqil M. ALmusawi ◽  
Thulfiqar S. Hussein ◽  
Muhaned A. Shallal

Recent developments in the production of ecologically friendly building composites have led to a renewed interest in the use of vegetable fibers as a reinforcement element. Traditional pure Plaster of Paris (POP) can suffer from the development of micro-cracks due to thermal expansion. Therefore, sisal fiber was studied for its potential as an ecological element to restrict and delay the development of micro-cracks in POP. Different sisal proportions of 0, 2, 4, 6, 8 and 10 wt. % of POP were used to characterize the physical and mechanical properties of POP at the ambient temperature. Then, the effects of temperatures of 25, 100, 200, 300, 400 and 500  were investigated. Results proved that the composite of 10% sisal fiber had the best mechanical properties. Also, when the fiber content was increased, the composite’s performance was enhanced, becoming better able to resist elevated temperatures. However, raising the temperature to 300 or above had a negative effect on the mechanical properties, which were significantly decreased due to the degradation of the sisal fiber. 


2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Qifang Xie ◽  
Lipeng Zhang ◽  
Shenghua Yin ◽  
Baozhuang Zhang ◽  
Yaopeng Wu

Fires are always known for seriously deteriorating concrete in structures, especially for those with certain carbonation due to long-time service. In this paper, 75 prism specimens were prepared and divided into four groups (three carbonated groups and one uncarbonated group). Specimens were tested under different temperatures (20, 300, 400, 500, 600, and 700°C), exposure times (3, 4, and 6 hours), and cooling methods (water and natural cooling). Surface characteristics, weight loss rate, and residual mechanical properties (strength, initial elastic modulus, peak, and ultimate compressive strains) of carbonated concrete specimens after elevated temperatures were investigated and compared with that of the uncarbonated ones. Results show that the weight loss rates of the carbonated concrete specimens are slightly lower than that of the uncarbonated ones and that the cracks are increased with raising of temperatures. Surface colors of carbonated concrete are significantly changed, but they are not sensitive to cooling methods. Surface cracks can be evidently observed on carbonated specimens when temperature reaches 400°C. Residual compressive strength and initial elastic modulus of carbonated concrete after natural cooling are generally larger than those cooled by water. The peak and ultimate compressive strains of both carbonated and uncarbonated concrete specimens increase after heating, but the values of the latter are greater than that of the former. Finally, the constitutive equation to predict the compressive behaviors of carbonated concrete after high temperatures was established and validated by tests.


2005 ◽  
Vol 498-499 ◽  
pp. 381-387
Author(s):  
Sandro Aparecido Baldacim ◽  
Olivério Moreira Macedo Silva ◽  
Claudinei dos Santos ◽  
Cosme Roberto Moreira Silva

The important factor to consider for successful ceramics composites development is the need of matching the whiskers and matrix characteristics, taking into account the chemical compatibility of the sintering aids utilized. The purpose of this work was to analyze and compare use of rare earth concentrate (CTR) and yttrium oxide, as sintering aids, and its influence in the densification and physical/mechanical properties of hot pressed and sintered Si3N4-SiC(w). The CTR powder materials present high yttrium oxide percentage and its production is cheaper than the additives usually used in ceramic materials, such as Y2O3. For physical and mechanical properties evaluation, specific mass, crystalline phases, micrographs analysis, microhardness and fracture toughness were measured, showing similar results between the two sintering aids. Therefore, this study shows the possibility of obtaining low processing cost products with the use of rare earth concentrate. Meanwhile, more characterization steps are necessary for analyzing its behavior at elevated temperatures.


2000 ◽  
Vol 646 ◽  
Author(s):  
P. S. Brenner ◽  
R. Srinivasan ◽  
R. D. Noebe ◽  
T. Lograsso ◽  
M. J. Mills

ABSTRACTThe mechanical properties and dislocation microstructure of single crystals with a range of compositions within the Fex-Ni60–x-Al40 pseudobinary system have been investigated, with the purpose of bridging the behavior from FeAl to NiAl. Experiments are focused on the compression testing of <001> oriented single crystals with compositions where x = 10, 20, 30, 40, and 50 (in atomic percent). Observations of a<111> dislocation morphologies at room temperature and both a<111> and non-a<111> dislocation activity at elevated temperatures are reported and discussed. Measurements of the yield strength, elastic modulus and strain hardening rates are reported, and the variation of strength with composition is correlated with dislocation dissociation and overall dislocation morphology.


Author(s):  
D.R. Munaf ◽  
M.S. Besari ◽  
M.M. IqbaP ◽  
And I. Kadir

Results of an experimental investigation on the effect of fly ash content, water cement (w/c) ratio of concrete prepared and cured at temperatures of ambience, 40°C and 60°C are presented in this paper. The mechanical properties investigated here include its workability, its behaviour under compression and splitting tension. Microscopic investigations were also carried out using SEM micrographic images to gain understanding of concrete at its microstructural level.The results indicate that high temperature increases early compressive strengths of concrete, but has decreasing effects on the strengths at later ages. The use of fly ash in concretes cast and cured at elevated temperatures improves the physical and mechanical properties of fresh as well as those of hardened concrete.Various mathematical models describing the properties of such concretes are considered at the end of this paper. The strength properties of high temperature fly ash concrete were best represented by a simple exponential function of time, while its stress-strain relationship could be best described by an exponential function of strain of a more complicated form.


1988 ◽  
Vol 125 ◽  
Author(s):  
Richard C. Dickinson

ABSTRACTCarbon/Carbon is a highly desirable material for use at elevated temperatures in structural applications due to its high strength-to-weight ratio and increasing strength with increasing temperatures.This presentation will survey the general methods used to fabricate and apply oxidation protection systems to these composites. This will be followed by an overview of typical physical and mechanical properties and selected results from oxidation rate studies.


Mechanik ◽  
2018 ◽  
Vol 91 (5-6) ◽  
pp. 438-442
Author(s):  
Magdalena Szutkowska ◽  
Marek Boniecki ◽  
Marcin Podsiadło ◽  
Andrzej Kalinka

The present study reports mechanical properties obtained by reinforcing alumina composites with Ti(C,N) in amount 30 wt.% prepared on the basis micro and nanoscale trade powders. The pressureless sintering PS in a vacuum and SPS method of sintering were used. Vickers hardness, density, Young modulus, wear resistance were evaluated. Fracture toughness (KIC) at ambient and elevated temperatures up to 1073 K, characteristic for tool work was measured. Physical and mechanical properties of the composites Al2O3/Ti(C,N)/ZrO2 based on the powders in microscale were compared with composites containing nanoscale powders in a range from 17 to 36 wt.%. Tested composites with nanoscale powders content reveal lower KIC (approx. 10÷30%) at ambient temperature in comparison to composites based on powders in microscale. However, in the elevated temperatures their fracture toughness increases up to 30%. The observation of the microstructure of tested composites was carried out using scanning electron microscopy.


2004 ◽  
Vol 120 ◽  
pp. 191-199
Author(s):  
J. Kohout

Long-term exposures of various industrial structural materials at sufficiently elevated temperatures cause substantial changes in materials structures and, consequently, substantial changes in their physical and materials properties. The paper is focused to the influence of thermodegradation of glass-fibre-reinforced polyamide 66 in dry air and gear oil on its mechanical properties. As the thermodegradation of polymer materials is diffusion controlled process, the paper starts with the description of water diffusion in tested material. Then a very simple degradation mechanism is proposed for modelling the main features of real degradation processes. Regression functions describing the changes in mechanical properties of polyamide details during exposure are verified by the fit of experimental results. In the end of the paper some general considerations about the changes in other structural materials during exposures are done and supported by some experimental results.


Author(s):  
Richard L. Colwell ◽  
Barry Messer ◽  
Jing Hu

Recent tests and data analysis have shown a correlation between the degree of hot working and elevated temperature mechanical properties of austenitic stainless steel piping and fittings, independent of the final solution anneal temperature and grain size. While this phenomenon is shown to occur in stabilized stainless steels by data in this paper, it has also been observed in non-stabilized austenitic stainless steel grades. It is understood that work-hardening results in higher material strength, and that annealing results in lower strength, as well as promoting dissolution of carbides and intermetallic phases. The “as-fabricated” mechanical properties of hot formed product are affected by the competition between strain-hardening, and softening due to recovery and recrystallization during hot working and subsequent solution annealing. It has been shown that increasing the amount of hot forming lowers the yield strength of austenitic stainless steel at elevated temperatures. Data is presented that calls into question the common belief that the solution anneal substantially eliminates strain-hardening resultant of prior forming. This paper discusses strengthening mechanisms, provides case histories, suggests mitigation practices, and stresses the importance of proper alloy characterization, and using conservative Code allowable safety factors.


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