Comparison of Physical and Mechanical Properties in Ceramics Composites Si3N4–CTR–AlN and Si3N4–Y2O3–AlN

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.

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..


2017 ◽  
Vol 41 (1) ◽  
Author(s):  
Mírian de Almeida Costa ◽  
Cláudio Henrique Soares Del Menezzi

ABSTRACT Thermo-mechanical treatment is a technique for wood modification in which samples are densified by means of heat and mechanical compression, applied perpendicularly to fibers, which under different combinations of time, temperature, and pressure increases wood density and thus improve some of its properties. This study aimed to treat thermo-mechanically parica plywood and observe the effects on its physical and mechanical properties. Specimens were submitted to two treatments, 120 and 150 ºC, remaining under pressure for seven minutes and, subsequently, under zero pressure for 15 minutes. Results showed a significant increase in specific mass from 0.48 g cm-3 to an average of 0.56 g cm-3, and a compression ratio of about 31.7% on average. Physical properties also varied significantly and results showed that treated samples swelled and absorbed more water than those untreated, leading to a greater thickness non-return rate. This indicates the proposed thermal treatments did not release the internal compressive stress generated during panel pressing, not improving its dimensional stability as a result. On the other hand, mechanical properties were positively affected, leading to an increase of 27.5% and 51.8% in modulus of rupture after treatments at 120 and 150 ºC, respectively. Modulus of elasticity and glue-line shear strength did not vary statistically and Janka hardness was 29.7% higher after treatment at 150 ºC.


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.


2008 ◽  
Vol 147 (1) ◽  
pp. 1-6 ◽  
Author(s):  
F.A. Guo ◽  
C.J. Xiang ◽  
C.X. Yang ◽  
X.M. Cao ◽  
S.G. Mu ◽  
...  

Author(s):  
Н.В. Ларионов

Мировые стремления к использованию космических аппаратов многоразового использования требует разработки и новых материалов. Углерод-керамические материалы обладают рядом специфических характеристик, которые позволяют рассматривать эти материалы как перспективные для использования в авиа и ракетостроении. Специфичность их свойств связана с методом получения и составом материала. Углеродные волокна обеспечивают высокие физико-механические показатели, а матрица из карбида-кремния повышает окислительную стойкость, даже в окислительной среде. The world's desire to use reusable space vehicles requires the development of new materials. Carbon-ceramic materials have a number of specific characteristics that allow us to consider these materials as promising for use in aviation and rocket science. The specificity of their properties is related to the method of preparation and composition of the material. Carbon fibers provide high physical and mechanical properties, and a silicon-carbide matrix increases oxidative resistance, even in an oxidizing environment.


2015 ◽  
Vol 663 ◽  
pp. 34-41 ◽  
Author(s):  
Fernanda Andreola ◽  
Isabella Lancellotti ◽  
Rosa Taurino ◽  
Cristina Leonelli ◽  
Luisa Barbieri

Virgin raw materials can be partially replaced by glass waste in order to reduce the environmental impact being its recycling a significant problem for municipalities worldwide. In Italy in 2013, approximately 1,600,000 tons of container glass have been collected but it was not possible to recycle all of them in the glass melting process.This work is focused on the valorization of glass waste as raw material in new cement and ceramic products, to convert it from an environmental and economic burden to a profitable, added-value resource in the formulation of new mixes. Several parameters, such as grinding, forming, firing, etc. have been studied.It has been optimized the grinding and the reclaiming step of waste to obtain an alternative raw material for hot and cold consolidation processes. Chemical, physical and mechanical properties of products were carried out. The results show new real possibilities to use high amounts of glass waste as an alternative raw material in products consolidated either by hot or cold techniques, reducing the management problems of the glass waste.


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