High Temperature Performance Resistance Research Articles

High-temperature resistance performance of silica aerogel composites through fiber reinforcement

Aiming to meet the fireproof requirements for bridges, three fiber/silica aerogel composites were fabricated using basalt fiber, a composite of basalt fiber and high silica glass fiber, and high silica glass fiber as the matrix. The dimensional, structural, mechanical, and thermal insulation stability of these composites under high-temperature heating ranging from 800 °C to 1000 °C were systematically studied. Upon high-temperature heating, the fracture and deformation basalt fiber occurred, leading to the breakage of the fiber skeleton and the aerogel integrity. This resulted in significant densification and a consequent decrease in porosity in the heated basalt fiber/aerogel composite and basalt fiber-high silica glass fiber/silica aerogel composite. Crystallization of basalt fiber began after heating to 800 °C and fully completed at 1000 °C. Besides, part of the high silica glass fiber in the basalt fiber-high silica glass fiber/silica aerogel composite crystallized at 900 °C and 1000 °C. These variations in micro-macro structures and phase compositions led to a substantial degradation of mechanical property and thermal insulation performance in the composites containing basalt fiber. In sharp contrast, the fiber skeleton and aerogel integrity remained relatively stable under high-temperature heating, enabling a synergistic thermal insulation effect of fiber and aerogel. The integrated fiber skeleton reduced the radiative thermal conductivity of the aerogel, while the unbroken aerogel protected the fiber from crystallization. Consequently, the mechanical property and thermal insulation performance of the high silica glass fiber/silica aerogel composite remained stable after high-temperature heating. The ultimate tensile strength and thermal conductivity of the pristine and 1000 °C-heated high silica glass fiber/silica aerogel composite were 0.74 MPa and 0.53 MPa, 0.0213 W/(m·K), and 0.0279 W/(m·K), respectively. This novel composite, exhibiting low thermal conductivity, high strength, excellent thermal stability, is expected to be a desirable candidate for bridge fireproof applications.

Synthesis and Characterization of a Resin/Acrylamide-2-acrylamide-2-methylpropane Sulfonate-Diallyl Dimethyl Ammonium Chloride-N-vinyl-2-pyrrolidinone Polymer Microcapsule Gelling Agent for Oil and Gas Field Transformation.

Deep carbonate rock oil and gas reservoir is an important support for increasing oil and gas storage and production at present. The environment of ultradeep and ultrahigh-temperature reservoirs has put forward higher technical requirements for reservoir modification acid technology. Moreover, gelling acid is the main acid solution for high-temperature reservoir acidizing transformation, with a temperature resistance of no more than 180 °C, and the gelling agent is one of the key factors restricting its high-temperature resistance performance. In this paper, AM, AMPS, DMDAAC, and NVP were used as monomers, oxidants, and reducing agents to prepare a high-temperature-resistant polymer gel through polymerization. At the same time, microcapsules were prepared by in situ polymerization using epoxy resin as the wall material. The indoor performance evaluation results indicate that the gelling agent is easily soluble in high-concentration acid solution and has good viscosity increasing effect. At 180 °C and 170 s-1 shear rate, 0.8% mass fraction of the gelling agent was dissolved in 20% mass fraction of hydrochloric acid. After shearing for 60 min, the viscosity remained at about 22.45 mPa·s, demonstrating good temperature resistance and shear resistance, and its performance was superior to existing commonly used gelling agent products.

Modification of basic refractory structure by zirconium dioxide nanopatricles

The paper presents data on the influence of zirconium dioxide micropowder addition, partially stabilized by yttrium, on high-temperature resistance performance of fired periclase products, as well as on some physical and physical –mechanical properties. Microscopic examination of the structure of highpurity synthetic periclase and zirconium dioxide micropowder was carried out. The possible mechanism of interaction of the introduced additive with impurities contained in periclase was determined. Substantial influence of zirconium dioxide micropowder on high-temperature properties of refractory was established.

Excellent high-temperature resistance performance of one-dimensional sepiolite coated membrane based on an organic-inorganic composite binder for lithium ionic batteries

A one-dimensional sepiolite (SNRs) coated membrane based on organic-inorganic composite binder (polyvinyl alcohol-phosphate inorganic binder, PVA-PIB) is constructed to solve the problems of poor high-temperature resistance and blockage pore of particle-coated membrane based on organic binders. Results show that the thermal shrinkage of SNRs-coated membrane based on PVA-PIB binder are low of 2.44% at high temperature of 200 °C, which is much lower than that of the membrane based on PVA binder (69.90%). The SNRs coating presents a porous structure with interlaced fibers which makes the porosity, the electrolyte uptake and the lithium ionic conductivity of the membrane much better than that of the Al2O3 particle-coated membrane. The wetting angle and Brunauer Emmett Teller results show that SNRs coating have good wettability and strong adsorbability to liquid electrolyte. The open circuit voltage-temperature and current-time curves show that the battery has excellent safety at high temperature of 180 °C and after 50 h constant-voltage charging. In addition, the battery based on the SNRs-coated membrane with PVA-PIB binder has good cycle and rate performance. The excellent high-temperature resistance and good electrochemical performance of SNRs-coated membranes is of great significance to the application of lithium ionic battery.

A study on frost and high-temperature resistance performance of supercooled phase change material-based flat panel solar collector

Easy freezing and overheating of the flat panel solar collector (FPSC) limits its large-scale application. In addition to the characteristics of high heat storage density and low price, inorganic supercooling phase change materials (PCMs) also have a large difference between their melting and freezing points, which fully meets the needs of FPSCs. In this paper, a new type of supercooled PCM as an FPSC was designed and studied, and a computational fluid dynamics (CFD) model was verified by experiments. Simulations were done to analyze the effects of different structures and PCM properties on the thermal efficiency and cooling rate of the collector. The results showed that the efficiency increase rate of the absorber plate was about 15% when the absorber plate was in direct contact with the PCM under neutralization. For the PCM with a melting point of 323.15 K and a supercooling degree of 30 K, the increase rate of the cooling time can reach more than 15% compared with that of a non-supercooled PCM. The structure of FPSC was optimized, and the thickness of PCM was studied in typical geographic areas. Except for Chengdu, the reliability index of the supercooled phase change material FPSC (SPCM-FPSC) in winter and summer was found to increase to more than 0.5 compared with 0.1 for ordinary FPSCs. It was found that the SPCM-FPSC significantly improved the freezing and high-temperature resistance of collectors in various regions. These results provide a strategy for the promotion and application of FPSCs in harsh outdoor environments.

The effects of cement type and expanded vermiculite powder on the thermo- mechanical characteristics and durability of lightweight mortars at high temperature and RSM modelling

The results of the impact of cement type and expanded vermiculite powder (EVP) on the thermal, mechanical characteristics and durability of lightweight mortars at high temperature and RSM modelling are presented in the paper. The lightweight mortars were fabricated by replacing fine aggregate with EVP in certain proportions. In the production of the mixtures, two different cement types namely, Portland cement (PC) and calcium aluminate cement (CAC) were used as binders and fine aggregates were replaced with EVP at the rates of 0%, 15%, 30% and 45%. The microstructure, thermal, mechanical properties and durability of PC and CAC mortars produced in this way were determined after standard curing for 28 days at temperatures ranging from 20 °C to 900 °C. Mechanical performance of mortar mixtures was evaluated based on compressive, flexural strength and ultrasonic pulse velocity (UPV). The durability of the specimens was also determined using porosity, water absorption and dry unit weight. Thermal conductivity and Scanning electron microscope (SEM) observations of 28-day mortar specimens were also evaluated. The response surface methodology (RSM) was adopted to develop the relation between parameters and response for thermal conductivity. The test results reported that lightweight refractory and insulating mortar can be manufactured by combined use of CAC and EVP when considered strength and durability and thermal performance after high-temperature exposure. Test results also pointed out that the combined use of CAC and EVP gained significant high-temperature resistance performance in terms of compressive strength as compared to PC blended mortar specimens.

Fabrication of Composite Unidirectional Cellular Metals by Using Explosive Compaction

Development of a small and highly efficient heat exchanger is an important issue for energy saving. In this study, the fabrication method of unidirectional (UniPore) composite cellular structure with long and uniform unidirectional cells was investigated to be applied as a heat exchanger. The composite UniPore structure was achieved by the unique fabrication method based on the explosive compaction of a particular arrangement of thin copper and stainless steel pipes. Slightly smaller thin stainless steel pipes filled with paraffin are inserted into small thin copper pipes, which are then arranged inside bigger and thicker outer copper pipes. Such an arrangement of pipes is placed centrally into a cylindrical explosion container and surrounded with explosive. Upon explosive detonation, the pipes are compacted and welded together, which results in a UniPore structure with a stainless steel covered inner surface of unidirectional pores to improve the corrosion resistance and high temperature resistance performance. Two different composite UniPore structures arrangements were studied. The microstructure of the new composite UniPore structure was investigated to confirm good bonding between the components (pipes).

Frost and High-temperature resistance performance of a novel dual-phase change material flat plate solar collector

In order to overcome the freezing and overheating problems of solar collectors, a novel dual-phase change material (PCM) flat plate collector was proposed in this research. There were two layers of PCMs in the solar collector, one layer material with a phase change temperature of 70 °C and another with a phase change temperature of 15 °C, respectively. They were placed in the space under the absorber plate in the dual-PCM collector. Frost and High-temperature resistance performance of the novel dual-phase change material solar collector was tested systematically in a laboratory. The experimental results showed that the time taken for the temperature of the absorber plate to increase from 60 °C to 78 °C could be prolonged by 1.6 h under high temperature conditions. Furthermore, the low-melting point PCM can substantially slow the temperature decrease of the collector by solidifying and releasing heat under the low-temperature conditions. And the time taken for the temperature of the absorber plate to decrease from 19 °C to 10 °C could be prolonged by 6.4 h and 3.1 h when low-melting PCM placed below high-melting PCM and the high-melting PCM placed below low-melting PCM. Thus it can be seen that the dual-PCM collector can be used to overcome the phenomenon of overheating and freezing. In addition, compared with an ordinary flat plate collector, the efficiency of the dual-PCM collector was increased by 24.1% and 19.6% when placing low-melting PCM below high-melting PCM and in the opposite condition respectively.

Improvement of high-temperature resistance on carbon fiber felt/portland cement composite friction material by Al2O3 sol–gel coating

The extrusion impregnation method is used to prepare carbon fiber felt/portland cement (CFF/PC) composite materials. The samples are placed into muffle furnace for ablation, but carbon fiber is oxidized at around 450 °C. To improve the oxidation resistance of carbon fiber, Al2O3 sol–gel (AS) is prepared to coat the surface of carbon fiber. The extrusion impregnation method is also used to prepare AS–CFF/PC composite materials. The samples are also ablated into muffle furnace at different temperatures. The results indicate that carbon fiber is uniformly dispersed and closely arranged in the matrix, presenting a three-dimensional network distribution. The bending and compressive strengths of CFF/PC composite materials are increased by 200% and 12% when compared with that of PC material at room temperature. The AS coating layer can effectively improve the antioxidant capacity of carbon fiber at high temperatures. The comparison reveals that AS–CFF/PC composite materials exhibit improved high-temperature resistance performance.

Drilling Technical Difficulties and Solutions in Development of Hot Dry Rock Geothermal Energy

The exploration and development of hot dry rock resources, first of all, needs to address the drilling issues in deep, hot, hard and unstable formations. By studying geological features and storage conditions of hot dry rocks, the key technical difficulties of hot dry rock drilling are presented. The high-temperature resistance performance index of oil and gas drilling technologies at home and abroad are investigated. The applicability of high effective rock breaking tools, MWD instruments, drilling fluid systems, well cementing and completion technologies are analyzed, and feasibility analyses have been conducted on gas drilling, dry wellbore cementing and foam pressurized drilling techniques. On the basis of the above analyses, the developing directions and issues urgently to be addressed about domestic hot dry rock drilling technology are discussed so as to provide references for drilling program optimization and drilling technology research in the development of hot dry rock geothermal energy.

The high-temperature resistance performance of TRC thin-plates with different cementitious materials: Experimental study

The paper focuses on an experimental investigation of the high-temperature resistance performance of TRC thin-plates with different cementitious materials. The effects of different cement matrix materials on the bearing capacity of the thin-plates were compared by using the unstressed residual temperature test method (URT). The results indicated that, from the macro view, TRC thin-plates with epoxy resin impregnated textile (type 1) exhibited obvious brittle failure characteristics no matter which kind of cementitious materials was selected. The bursting ratio of type 1 was 100% when the target temperature (TR) reached 400°C; while TRC thin-plates with non-impregnated textile (type 2) were characterized by ductility. When TR⩽600°C, no significant difference in the bearing capacity was observed between the type 2 specimens using alumina cement as matrix (CAC specimens) or using ordinary Portland cement as matrix (OPC specimens). The bearing capacity of CAC specimens after 800°C could be up to 32% of that at room temperature, which is 1.7 times of OPC specimens. Furthermore, the surface of CAC specimens did not crack or flake off which proved a better high-temperature resistance performance than OPC specimens. On the other hand from the micro perspective, thermogravimetric analysis, pore distribution and micro-structural analysis were performed to evaluate the degradation of the damaged specimens using thermogravimetric analyzer (TGA), mercury intrusion porosimeter and an environmental scanning electron microscope (SEM), respectively. The results showed that declination of bearing capacity after high temperature was mainly due to degraded filaments, the increasing pore size of matrix and the decreasing bonding between fiber and matrix. The average pore diameter of CAC matrix was only 28% of OPC matrix after 800°C; and the loss in strength of CAC matrix was obviously less severe than that of OPC matrix between 600°C and 800°C. Conclusively, using high alumina cement as matrix could effectively reduce the thermal degradation of the matrix at high temperatures.

High-temperature resistance performance of an inorganic adhesive for concrete structures strengthened with CFRP sheets

Organic epoxy matrices have been widely used in the FRP reinforcing technique, but they have serious disadvantages of poor high-temperature resistance. An inorganic adhesive is invented to replace the organic adhesive. For the inorganic adhesive at normal temperature and different high temperatures, the microstructure and phase composition are investigated by means of X-ray diffraction (XRD) and SEM respectively. Results show that inorganic adhesive can resist at least 600 °C high temperature. Fire-resistance performance of inorganic adhesive can meet the requirements of fiber reinforced polymer (FRP) strengthened RC structures.

Development of an Aluminized Multi‐Phase Steel with Dual Phase Properties for High Temperature Corrosion Resistance Applications

A high strength, high Mn, Cr‐Mo containing multi‐phase steel grade was aluminized with a 90 wt% Al – 10 wt% Si alloy coating, using a laboratory hot‐dip simulator. The adhesion of the coating to the steel strip was evaluated and the microstructure of the as deposited material was assessed. The coated sheet steel was tested at high temperatures by monitoring the weight gain of the samples and their mechanical properties as a function of time. It was found that the thermal properties of the aluminized sheet were excellent. The analysis of the coating/substrate interface revealed the dissolution of brittle intermetallic phases, explaining the excellent high temperature resistance performance of the Al‐Si coating up to temperatures as high as 900°C. In addition, the use of a continuous annealing cycle common in current aluminizing lines, resulted in a dual phase microstructure.