Experimental Study on Mechanical Property and Pore Distribution of Limestone Specimens after Heat Treatment under Different Heating Conditions

The thermal effect of rocks not only depends on the temperature level but also may be influenced by the factors including heating environment, heating rate, and cooling method. In this study, approximate vacuum (V) and air circulation (A) heating condition are, respectively, applied on the limestone specimens in the whole heating process. Then, physical, mechanical, and nuclear magnetic resonance (NMR) tests were carried out to investigate the effect of heating conditions on the rock properties. The results show that heating conditions have significant effects on mechanical properties of limestone specimens (including peak strength, elasticity modulus, secant modulus, and crack initiation stress), which are due to the interference effect on the oxidation and thermal decomposition. It is worth noting that the significant temperature range of the heating condition is 450 ∼ 750°C, during which the mechanical performances of heat-treated specimens under V condition obviously outperform those under A condition. Combining the NMR results and the microstructure images from scanning electron microscope (SEM) technology, the evolution of pore distribution was revealed. As temperature increases from room temperature to 900°C, porosity increases gradually. However, pore distribution changes from small and medium pores dominating to large pore dominating and then to medium pore dominating. For limestone specimens after high-temperature treatment above 450°C, mineral crystals may melt and reconsolidate, filling in some of the previously large pores generated by thermal decomposition.

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Quality Improvement of CNT by Thermal Treatment and Enhancement of Properties of CNT/Polymer Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.772.23 ◽

2018 ◽

Vol 772 ◽

pp. 23-27

Author(s):

Takashi Amemiya ◽

Toshiyuki Yasuhara

Keyword(s):

Polymer Composites ◽

Mechanical Characteristics ◽

Polymer Matrix Composites ◽

Lower Surface ◽

Temperature Treatment ◽

High Temperature Treatment ◽

Matrix Composites ◽

High Quality ◽

Heat Treated ◽

Double Wall

Since CNTs (carbon nanotubes) have excellent electrical and mechanical characteristics, their application as fillers for polymer matrix composites is expected to have great potential. The purpose of this study is to clarify the effect of CNT’s crystallinity quality, which is given by high temperature treatment (i.e. annealing), on the properties of CNT/polymer composites. In this study, double wall type CNT (DWNT) and multi wall type CNT (MWNT) were used and heat treated at up to 2000°C to achieve highly improved crystallinity. Electrical and mechanical properties of the CNT/polymer composites were compared with the various CNT’s crystallinity qualities as measured by ID/IG ratios. As a result, although the composites with higher quality CNTs showed considerably lower surface resistivities, however the same composites had lower Young's modulus and tensile strengths. The reason is thought to be that the high quality CNT has low surface activity and weak adhesion between the polymer and the CNT surface. This suggests that CNTs with higher quality do not always contribute to the improvement to the properties of CNT/polymer composites.

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Prepregs for Temperature Resistant Composites

Materials ◽

10.3390/ma12234012 ◽

2019 ◽

Vol 12 (23) ◽

pp. 4012 ◽

Cited By ~ 1

Author(s):

Eliška Haincová ◽

Pavlína Hájková ◽

Jan Kohout

Keyword(s):

Tensile Properties ◽

Preparation Method ◽

Temperature Treatment ◽

High Temperature Treatment ◽

Matrix Composites ◽

Heat Treated ◽

Fabric Composites ◽

Original Strength ◽

Alkali Activated ◽

Inorganic Matrix

In this paper, carbon fabric reinforced inorganic matrix composites were prepared. The inorganic matrix based on alkali activated aluminosilicate was used because of its resistance to fire and the temperatures up to 1000 °C. Influence of heat treatment of fabric, high temperature treatment of composite and preparation method on the mechanical properties and morphology of the composites were studied. The preparation of composites with the subsequent steps of impregnation, layering and curing of the composites was compared with the prepreg preparation method, which separates the impregnation of the reinforcement from the production of the composite. The SEM photographs show no differences in morphology between composites prepared from heat treated fabric and composites prepared from original fabrics. All four series of samples were comparatively saturated with matrix. Despite this, tensile properties of heat-treated fabric composites were negatively affected. While composites with heat-treated fabric reached the tensile strength up to 274 MPa, composites prepared without heat-treated fabric exhibited strengths higher than 336 MPa. Samples exposed to temperatures reaching 600 °C retained up to 40% of their original strength. The effect of composite preparation method on the tensile properties of the composites has not been proved.

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Effect of high-temperature treatment in air on the surface area and porous texture of zirconium dioxide prepared by thermal decomposition of the nitrate

Journal of Chemical Technology and Biotechnology ◽

10.1002/jctb.5030320725 ◽

2007 ◽

Vol 32 (7-12) ◽

pp. 882-887 ◽

Cited By ~ 5

Author(s):

Carlos Otero Areán ◽

José M. Fern Ández Colinas ◽

Andrés Mata Arjona ◽

María A. Villa García

Keyword(s):

Thermal Decomposition ◽

High Temperature ◽

Surface Area ◽

Zirconium Dioxide ◽

Temperature Treatment ◽

High Temperature Treatment ◽

Porous Texture

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Spectroscopic Identification of Amber Imitations: Different Pressure and Temperature Treatments of Copal Resins

Crystals ◽

10.3390/cryst11101223 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1223

Author(s):

Ting Zheng ◽

Haibo Li ◽

Taijin Lu ◽

Xiaoming Chen ◽

Bowen Li ◽

...

Keyword(s):

Spectral Characteristics ◽

Experimental Methods ◽

Temperature Treatment ◽

High Temperature Treatment ◽

Resonance Spectroscopy ◽

Spectroscopic Methods ◽

Spectral Changes ◽

Multi Stage ◽

Heat Treated ◽

Spectroscopic Identification

Copal resins can be treated with heat and/or pressure to imitate ambers in the gem market. To explore the effects of different modification conditions on post-treatment spectral changes, five experimental methods with different temperature–pressure parameters were designed to modify two types of copal resins. The treated copal resins were examined by infrared, Raman and nuclear magnetic resonance spectroscopy. Results indicate that all the treatment methods simulate the maturation process, with spectral characteristics becoming more similar to those of ambers. Multi-stage heat–pressure treatment has the most significant effect on Colombia and Madagascar copal resins, with their spectra being similar to those of Dominican and Mexican ambers. Rapid high-temperature treatment at 180 °C modified the Borneo copal resin, with its infrared spectrum developing a “Baltic shoulder” resembling that of heat-treated Baltic amber. Even though there are many similarities between treated copal resins and natural ambers, they can still be distinguished by spectroscopic methods.

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Effect of high temperature treatment of Vicia faba roots on the oxidative stress enzymes in leaves.

Acta Biochimica Polonica ◽

10.18388/abp.1997_4427 ◽

1997 ◽

Vol 44 (2) ◽

pp. 315-321 ◽

Cited By ~ 2

Author(s):

M Filek ◽

R Baczek ◽

E Niewiadomska ◽

M Pilipowicz ◽

J Kościelniak

Keyword(s):

Oxidative Stress ◽

Vicia Faba ◽

Temperature Treatment ◽

Activity Analysis ◽

High Temperature Treatment ◽

Sod Activity ◽

Heat Treated ◽

Oxidative Stress Enzymes ◽

Stress Enzymes ◽

Cell Fractions

The following types of superoxide dismutase (SOD) have been found in the leaves of Vicia faba: one isoenzyme of Mn-SOD and four isoenzymes of Cu/Zn-SOD. The treatments of roots with boiling water caused an increase of SOD activity in the leaves. The highest increase was measured after 5 s of the treatment. It was accompanied by a significant increase in catalase activity. Analysis of cell fractions' revealed an increase of SOD activity in the plastids and mitochondria isolated from the leaves of those plants whose roots were heat-treated. However, there was no distinct change of SOD activity in the cytosolic fraction. The possibility of an electric wave intervention inducing oxidative stress in the leaves is discussed.

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