scholarly journals Physical Alteration and Color Change of Granite Subjected to High Temperature

2021 ◽  
Vol 11 (19) ◽  
pp. 8792
Author(s):  
Andor Németh ◽  
Ákos Antal ◽  
Ákos Török
Keyword(s):  
Heat Treatment ◽  
Bulk Density ◽  
Wave Velocity ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Color Change ◽  
Surface Hardness ◽  
P Wave ◽  
Ultrasound Wave ◽  
Surface Strength

Cylindrical specimens obtained from the monzogranite host rock of the National Radioactive Waste Repository of Hungary were tested at room temperature and 250 °C, 500 °C, and 750 °C of heat treatment. Reflectance spectra (color), bulk density, Duroskop surface hardness, and ultrasound-wave velocity values were measures before and after thermal stress. According to CIE L*a*b* colorimetric characteristics, the specimens’ color became brighter and yellower after the heat treatment. At 750 °C, a significant volume increase was recorded linked to the formation of macro-cracks, and it also led to the drop in bulk density. Smaller temperature treatment (250 °C) caused a minor decrease in density (−1.3%), which is higher than the reduction of density at 500 °C (−0.8%). Duroskop surface strength showed a slight decrease until 500 °C, and then a drastic decline at 750 °C. P- and S-wave velocity values tend to decrease uniformly and significantly from room temperature to 750 °C. P-wave velocity and Duroskop values have a high exponential correlation at elevated temperatures. Physical alterations originated from the differential thermal-induced expansion of minerals, the formation of micro-cracks. Mineralogical changes at higher temperatures also contribute to the volume change and the loss in strength.

scholarly journals Heat-related Changes of Density, P-wave Velocity, and Surface Hardness of Granite

2021 ◽  
Author(s):  
Andor Németh ◽  
Ákos Török
Keyword(s):  
Heat Treatment ◽  
Radioactive Waste ◽  
Physical Properties ◽  
Bulk Density ◽  
Wave Velocity ◽  
Room Temperature ◽  
Surface Hardness ◽  
P Wave ◽  
P Wave Velocity ◽  
Laboratory Test Results

Low- and intermediate-level radioactive waste is stored in the National Radioactive Waste Repository in Bátaapáti in Hungary. The repository is located in the Carboniferous Mórágy Granite Formation. This paper focuses on heat-related changes of physical properties such as bulk density, P-wave velocity, P-wave modulus, and Duroskop surface hardness of the dominant lithology: monzogranite. Cylindrical specimens were tested at laboratory conditions (22 °C) and were heat-treated up to 250 °C, 500 °C, and 750 °C. The properties were measured before and after the thermal strain. After heat-treatment, the monzogranite samples became brownish, and at 750 °C, cracks appear at the surface of the specimens. Laboratory test results show that bulk density values slightly decrease from room temperature to 250 °C treatment and further dropped at 500 °C and especially at 750 °C. P-wave velocity values and the connected P-wave modulus tend to decrease from room temperature to 750 °C significantly. Duroskop rebound values show slight declines in the surface strength of the specimens until 500 °C, and then a drastic decline at 750 °C. Heat treatment tends to alter the physical properties of the monzogranite. From room temperature to 500 °C, a slight but apparent decrease between 500 °C and 750 °C significant reductions in the bulk density, P-wave velocity, and Duroskop values. Behind the physical alterations are the different thermal-induced expansion of minerals and mineral alteration at elevated temperatures.

The Heritage Stone of Nossa Senhora de Guadalupe Church, Mouçós, North of Portugal: Characterisation and Glyptography

2021 ◽  
Author(s):  
David Freire-Lista ◽  
Bruno Campos ◽  
Patricia Moreira da Costa
Keyword(s):  
Water Absorption ◽  
Bulk Density ◽  
Wave Velocity ◽  
Effective Porosity ◽  
P Wave ◽  
Building Stones ◽  
Thin Sections ◽  
P Wave Velocity ◽  
The Mean ◽  
The Church

<p>Granite is the most important building stone in the north of Portugal. The importance of the stones in this region is evidenced by the pre-Roman roots Mor (r), Mur (r) and Mour of place names such as Montemuro, Moreiras, Mouçós, and Mourelhe. These roots indicate the existence of building stones used since ancient times in these places.</p><p>The quarries of the main building stones of historical buildings were generally in the vicinity of the buildings. Formerly, stonemasons carved mason's marks on ashlars. The mason's marks are lapidary signs to indicate the work carried out by each one. The mason's marks are generally symbolised by the initial of the stonemason's name. They are often found on dressed stones in buildings and in other public structures.</p><p>Nossa Senhora de Guadalupe church of Mouçós (possibly 16<sup>th</sup> century) has typical characteristics from the late Romanesque. It is located in Vila Real (North of Portugal). It is made up of three volumes: a single nave, a lower rectangular apse, and a sacristy attached to the apse. The exterior of this church is preserved almost unaltered in its original state. Each of the granite ashlars that make up this church has a mason's mark in the center of its face.</p><p>The mason's marks of the church have been identified; all the ashlars with visible mason's marks have been mapped, and a glyptographic study has been carried out. This has made it possible to calculate the number of stonemasons that worked in the construction of the church and the number of ashlars that were transported in each carriage, and to determine the construction phases of the church.</p><p>Eight cubic samples have been cut to calculate the granite’s hydric properties (effective porosity, water absorption and bulk density) according to UNE-EN:1936. Ultrasound wave velocity was measured according to UNE-EN:14579. Furthermore, three thin sections have been made to characterise the granite petrographically under a polarisation microscope Leica DM-4500-P. A mosaic of photomicrographs has been made to evaluate the petrographic properties.</p><p>There are six main types of mason's marks in Nossa Senhora de Guadalupe Church. All quarrymen extracted the stones from the same quarry, or from nearby quarries. The mean effective porosity of the building granite is 3.2%±0.3, and the mean water absorption is 1.2%±0.1. Its mean bulk density is 2566 kg/m<sup>3</sup>±61.0 and its ultrasound P wave velocity is 2920 m/s±98.3.</p><p>The mason's marks are preserved because of the excellent petrographic and petrophysical properties of Mouçós granite. Further, Nossa Senhora de Guadalupe church was protected with lime plaster during the past centuries, and the plaster was not removed with the projection of abrasive particles.</p><p>The use of analytical techniques such as petrography, ultrasonic P wave velocity and the determination of hydric properties will guarantee the quality and durability of a sustainable restoration.</p><p>The historical quarries, forms of traditional stone extraction and uses of Mouçós granite constitute a heritage that must be safeguarded.</p><p>Acknowledgements: The Fundação para a Ciência e a Tecnologia (FCT) of Portugal. CEECIND/03568/2017.</p>

scholarly journals The Influence of Post-Heat-Treatments on the Tensile Strength and Surface Hardness of Selective Laser Melted AlSi10Mg

2017 ◽  
Vol 370 ◽  
pp. 171-176 ◽  
Author(s):  
Leonhard Hitzler ◽  
Amandine Charles ◽  
Andreas Öchsner
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Heat Treatments ◽  
Age Hardening ◽  
Material Strength ◽  
Post Heat Treatment ◽  
Treatment Procedure

Recent investigations revealed major fluctuations in the material properties of selective laser melted AlSi10Mg, which corresponded with the varying precipitation-hardening state of the microstructure, caused by the differing dwell times at elevated temperatures. It was indicated that a subsequent heat treatment balances the age-hardening and results in a homogenized material strength. In order to further investigate this statement selective laser melted AlSi10Mg samples were subject to multiple post-heat-treatments. Subsequently, the surface hardness and tensile strength was determined and compared with the as-built results. The post-heat-treatment led to an arbitrary occurrence of rupture, indicating a successful homogenization, coupled with a remarkable improvement in ductility, but to the costs of a lowered tensile strength, which was highly dependent on the chosen heat-treatment procedure.

Dissolution and oxidation of mudstone under stress

1993 ◽  
Vol 30 (1) ◽  
pp. 60-70 ◽  
Author(s):  
Masahiro Chigira
Keyword(s):  
Wave Velocity ◽  
Color Change ◽  
Effective Diffusivity ◽  
P Wave ◽  
Hydrogen Ions ◽  
P Wave Velocity ◽  
Long Time ◽  
Diffusion Of Hydrogen ◽  
Acid Labile ◽  
Dissolution Front

Weathering of soft mudstone in nature, characterized by the presence of an oxidized zone and an underlying dissolved zone, was simulated in the laboratory in 15 °C water with a pH of 3–7 and dissolved oxygen contents of 4–16 mg/L under stresses up to 0.49 MPa for as long as 70 days. When the water is acid, hydrogen ions diffuse from the rock–water interface through the rock and attack acid-labile calcite in mudstone preferentially and easily at a well-defined dissolution front, leaving a dissolved zone behind the front. Density decreases, porosity increases, ultrasonic P-wave velocity decreases, and shear strength decreases in the dissolved zone. The dissolution front migrates toward unreacted rock, and the migration rate is controlled by the diffusion of hydrogen ions in the reacted dissolved zone, so the rate is influenced by the stress exerted on the rocks; the effective diffusivity becomes smaller when the rock is stressed. Oxygen also diffuses through the rock to a well-defined oxidation front and changes the rock color from greenish grey to pale brown by oxidation. Slight deterioration occurs with the color change and change in density, P-wave velocity, and porosity. Depletion of pyrite by oxidation and the complete color change take a long time in comparison with the slight color change. Chlorite seems to transform into smectite in acid and highly oxidizing conditions. Key words : mudstone, dissolution, oxidation, weathering.

scholarly journals Compressive Behavior of Recycled Mortar After Exposure to High Temperatures

2016 ◽  
Vol 10 (1) ◽  
pp. 807-812 ◽  
Author(s):  
Jiong-Feng Liang ◽  
Ze-Ping Yang ◽  
Ping-Hua Yi ◽  
Jian-Bao Wang
Keyword(s):  
Compressive Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Color Change ◽  
Engineering Application ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Compressive Behavior ◽  
Natural Sand ◽  
Obvious Relation

The possibility of using fine recycled concrete aggregate as a substitute for natural sand are relatively limited. In order to promote it for engineering application, this paper reports the effect of elevated temperatures from room temperature to 600oC on the compressive behavior of mortars containing recycled fine concrete aggregate was investigated. It is found that no obvious relation between the color change and the recycled mortars replacement percentage.And the mass loss of recycled mortars is larger than that of normal mortars.The compressive strength of recycled mortars declines significantly as the temperature rises. The elastic modulus of recycled mortars decreased with the increase in temperature, and the decrease is much quicker than the decrease in compressive strength.

Nitriding

2005 ◽  
pp. 227-244
Keyword(s):  
Heat Treatment ◽  
Surface Hardening ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Ion Nitriding ◽  
Gear Teeth ◽  
Gas Nitriding ◽  
Aerospace Applications ◽  
High Shock ◽  
Hardening Heat Treatment

Abstract Nitriding is a surface hardening heat treatment that introduces nitrogen into the surface of steel while it is in the ferritic condition. Gas nitriding using ammonia as the nitrogen-carrying species is the most commonly employed process and is emphasized in this chapter. Nitriding produces a wear- and fatigue-resistant surface on gear teeth and is used in applications where gears are not subjected to high shock loads or contact stress. It is useful for gears that need to maintain their surface hardness at elevated temperatures. Gears used in industrial, automotive, and aerospace applications are commonly nitride. This chapter discusses the processes involved in gas, controlled, and ion nitriding.

A research on the effect of retrogression and re-aging heat treatment on hot tensile properties of AA7075 aluminum alloys

2021 ◽  
pp. 1-23
Author(s):  
Talha Sunar ◽  
Dursun Ozyurek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Ductile Fracture ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Xrd Analysis ◽  
Tensile Tests ◽  
Heat Treatments ◽  
Tensile Behaviour ◽  
Heat Treated

Abstract Aluminium alloys are preferred in most industries due to the functional properties they provide. It is known that alloys that can be processed with heat treatments shows better mechanical properties. 7xxx series alloys can be processed vi heat treatments and are often used in environmental conditions such as extreme temperatures and corrosive environments. Corrosive sensitivities such as stress corrosion cracking (SCC) can be observed with the effect of working conditions. It is known that retrogression and re-aging (RRA) heat treatment provide corrosion resistance and decrease the SCC velocity. The purpose of this study is to examine the tensile behaviour of annealed and retrogression-re-aging (RRA) heat treated AA7075 alloys at elevated temperatures. The mechanical properties of the alloys were investigated by conducting tensile tests at room temperature (RT), 100, 200, and 300°C. Hardness tests were performed at room temperature on the samples which were taken from tensile test specimens after tensile tests. The potential effects of test temperature on mechanical and microstructural properties were examined. The annealed and RRA heat treated alloys were characterized by scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis. As a result, an increase in strength and hardness of the RRA treated AA7075 alloys was observed. Ductility of the RRA alloy was lower compared to the annealed AA7075 alloy. Fracture surface examinations showed that there was a semi-ductile fracture below 200°C and ductile fracture at temperatures of 200 and 300°C. Ductility was observed to increase with increasing temperature.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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