Calibration of high-temperature furnace assemblies for experiments between 200 and 600 MPa with end-loaded piston-cylinder apparatuses

Vlach, Sílvio Roberto Farias; Naranjo, Salazar; Torres-Corredor, Johan S.; Carvalho, Paulo Rafael de; Mallmann, Guilherme

doi:10.1590/2317-488920192018090

Cited by 3 publications

(2 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This metal capsule was inserted into a 3/4" concentric furnace assembly consisting of crushable MgO, which acts as a sample holder fixer, graphite heater, pyrex (B-silicate) glass (spacer), and NaCl sleeves to maintain the almost friction-free sample, besides steel plugs. An alumina two-bore insulator allowed thermocouple insertion and temperature measures on the capsule top-end, isolated from the thermocouple probe with a thin Al disk [56]. The 3/4" furnace assembly used in the studies can be seen in Figure 1.…”

Section: Precursor Minerals and Piston-cylinder Apparatusmentioning

confidence: 99%

Electrical Resistance Evolution of Graphite and Talc Geological Heterostructures under Progressive Metamorphism

Nobre,

de Andrade,

Salazar-Naranjo

et al. 2023

Self Cite

View full text Add to dashboard Cite

The electrical properties of isolated graphene established precedents for studies of electrical superconducting materials at room temperature. After the discovery of stabilized graphene and graphite nanoplatelets in a geological context, the interest in characterizing the properties of these minerals arose. This work evaluates the electrical resistance evolution of mineral graphite and talc heterostructures under progressive metamorphism simulated in the laboratory. The experiments were conducted on an end-loaded piston-cylinder apparatus. This equipment allows for the application of equal pressure in all sample directions (lithostatic pressure) and heating, simulating geological phenomena. The behavior of two sets of mineral samples were compared: graphite and talc in billets and powder. Samples in billets were submitted to treatments at 400 °C and 4 kbar; 400 °C and 6 kbar; and 700 °C and 9 kbar. The powder samples were subjected to 700 °C and 9 kbar, with two ways of disposing the mineral powders (mixed and in adjacent contact) beyond 900 °C and 9 kbar (in adjacent contact). The results show that the samples in billets had lower electrical resistance when compared to the powder samples. The lowest electrical resistance was observed in the sample treated at 400 °C and 6 kbar, conditions that are consistent with metamorphic mineral assemblage observed in the field. Powdered samples showed better cleavage efficiency during the experiment, resulting in thinner flakes and even graphene, as pointed out by Raman spectroscopy. However, these flakes were not communicating, which resulted in high electrical resistance, due to the need for an electrical current to pass through the talc, resulting in a Joule effect. The maximum electrical resistance obtained in the experiment was obtained in the sample submitted to 900 °C, in which talc decomposed into other mineral phases that were even more electrically insulating. This work demonstrates that electrical resistance prospecting can be an efficient tool to identify potential target rocks with preserved mineral nanometric heterostructures that can form an important raw material for the nanotechnology industry.

show abstract

Section: Precursor Minerals and Piston-cylinder Apparatusmentioning

confidence: 99%

Electrical Resistance Evolution of Graphite and Talc Geological Heterostructures under Progressive Metamorphism

Nobre,

de Andrade,

Salazar-Naranjo

et al. 2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…The capsule was loaded into a 3/4" furnace assembly that contained the reactants (starting sample) was formed concentric layers composed by crushable MgO which acts as a sample holder fixer, graphite heater, pyrex (B-silicate) glass (spacer) and NaCl sleeves to maintain the almost friction-free sample [25], besides steel plugs (Figure 2). The system assembly of the piston-cylinder apparatus complies with VLACH et al [26] procedures. An alumina two-bore insulator allows thermocouple insertion and temperature measures on the capsule top-end, isolated from the thermocouple probe with a thin Al disk.…”

Section: Sample Preparation For Piston-cylinder Apparatusmentioning

confidence: 99%

Simulation of geological graphene genesis by the piston-cylinder apparatus

et al. 2022

View full text Add to dashboard Cite

Stable natural graphene occurs in graphite-and phyllosilicate-bearing low-grade metamorphic rocks. The present work simulates the process of geological formation of graphene using a piston-cylinder apparatus, promoting diffusion between talc and graphite at 700ºC and 900 MPa for a period of 24 h. The experimental products were analyzed by optical and scanning electron microscopy for description of the microstructures formed between the mineral precursors. The talc-graphite diffusion zone was also analyzed by Raman spectroscopy. Results indicate that graphite becomes progressively more deformed near the talc diffusion zone and eventually undergoes cleavage. Graphene becomes stable on the talc substrate in the center of diffusion zone. Therefore, the search for deposits of natural graphene and other nanomaterials in geological context is promising.

show abstract

New Experimental Constraints for the Evolution and Thermobarometry of Alkali Ultrabasic to Intermediate Igneous Rocks

Salazar-Naranjo,

Vlach

2023

Journal of Petrology

View full text Add to dashboard Cite

We report new experimental data from ultrabasic basanite and ultrabasic tephrite as starting material compositions in the 1350 - 1000°C temperature range. Crystallization experiments under low- to high-pressure (0.5 to 2.0 GPa) were carried out under reduced conditions (≈CCO buffer), while one-atmosphere, anhydrous, experiments were performed ranging from reduced to oxidized conditions (-2 ≤ QFM ≤ +2). The results highlight the ƒO2 role on the silica saturation of the alkali liquids differentiated from these primary ultrabasic magmas, on the mineral assemblage, and its composition. The liquid lines of descent (LLDs) from ultrabasic basanite are sodic and strongly SiO2-undersaturated, whereas from ultrabasic tephrite, the LLDs are sodic-potassic/potassic for both weakly SiO2-undersaturated and SiO2-saturated compositions, being more silica saturated under oxidized conditions. At the lowest temperature experiments, the percentage of liquid remaining is significantly higher in the basanite-derived products (ca. 35 wt.%) than in tephrite, indicating that the equivalent magmas are more prone to produce larger quantities of evolved melts. The best obtained Fe-Mg olivine/melt and clinopyroxene/melt exchange coefficients for these alkali compositions considering the new and available data are ${K_D}_{Fe^{2+}- Mg}^{Ol- Alkali\ melt}=0.285\pm 0.014$ and ${K_D}_{Fe^{2+}- Mg}^{Cpx- Alkali\ melt}=0.245\pm 0.008$, slightly lower than those observed in tholeiitic melts. Clinopyroxene compositions are Ti-Al-rich and Si-poor as compared with common clinopyroxenes in subalkali systems. We suggest that Ti should be allocated in the tetrahedral sites substituting for Si, and that its contents are inversely correlated with pressure. Our results allow a simple new barometer based on clinopyroxene-only compositions, as follows:$$ P\left(\pm 0.16\ GPa,1\sigma \right)=16.028\left(\pm 1.042\right) Na-6.715\left(\pm 0.727\right)\frac{Ti}{Ti+ Al(t)}+0.494\left(\pm 0.441\right) Si+0.144\left(\pm 0.079\right) $$ where Na, Ti, Al(t), and Si are molar proportions relative to 6O. This formulation accounts for the jadeite (NaAlSi2O6) component, herein computed from the Na contents, corrected for the Ti-diopside (CaMgTi2O6) component in clinopyroxene and also considers the evolutionary trend from Mg-augite to ferroan diopside. It applies to alkali ultrabasic to intermediate compositions in the examined P-T-ƒO2 range, resulting in more accurate estimates than the available calibrations. The MgO-in-melt thermometer was optimized for the studied compositions at one-atmosphere pressure and anhydrous conditions, as follows:$$ T\ \left(\pm 5{}^{\circ}C,1\sigma \right)=27.35\left(\pm 0.65\right)\ \left({MgO}^{liq}\right)+984\left(\pm 4\right) $$ which provides much more reliable liquidus temperatures for these alkali systems. Given data restriction, this formulation may be expanded to include the pressure effects for relatively low-H2O (< 3 wt.%) systems as:$$ T\ \left(\pm 20{}^{\circ}C,1\sigma \right)=27.35\left(\pm 0.65\right)\left({MgO}^{liq}\right)+80.20\left(\pm 5.50\right)P(GPa)+981\left(\pm 4\right) $$

show abstract

Calibration of high-temperature furnace assemblies for experiments between 200 and 600 MPa with end-loaded piston-cylinder apparatuses

Cited by 3 publications

References 14 publications

Electrical Resistance Evolution of Graphite and Talc Geological Heterostructures under Progressive Metamorphism

Electrical Resistance Evolution of Graphite and Talc Geological Heterostructures under Progressive Metamorphism

Simulation of geological graphene genesis by the piston-cylinder apparatus

New Experimental Constraints for the Evolution and Thermobarometry of Alkali Ultrabasic to Intermediate Igneous Rocks

Contact Info

Product

Resources

About