High Compressibility ZrTiHfV0.5Nb0.5CX Refractory High-Entropy Alloys

Refractory high-entropy alloys (RHEAs) have outstanding characteristics such as high melting point, high temperature oxidation resistance and corrosion resistance, which shows very promising application in the high temperature field; but commonly the refractory high-entropy alloys have the disadvantages of high density and poor plasticity. In this work, ZrTiHfV0.5Nb0.5Cx(x=0, 0.06, 0.12, 0.2) alloys are prepared by vacuum non-consumable arc-melting with ZrTiHfV0.5Nb0.5based. The density of ZrTiHfV0.5Nb0.5C0.2alloy is reduced to 8.014g/cm3compared to ZrTiHfV0.5Nb0.5(8.135g/cm3). The microstructure, static and high-temperature compressive strength are investigated. XRD and EDS analysis show that the microstructure of ZrTiHf0.5Nb0.5Cxalloys consists of BCC phase and HfC phase. ZrTiHfV0.5Nb0.5Cxalloys have high compression plasticity with plastic strain> 40% at room temperature, no fracture occurred during compression and yield stress is closed to 1GPa.

TO TESTING OF STEEL FIBRE REINFORCED CONCRETE AT ELEVATED TEMPERATURE

Addition of steel fibres improves properties of concrete. The lack of information considering tensile and post cracking behaviour of SFRC at elevated temperatures is an obstacle on the wide use of this composite material. This work presents an experimental study of steel fibre reinforced concrete subjected to high temperature. Compressive strength, split tensile strength and ultimate bending strength were evaluated. The specimens were heated by ceramic heaters and then repacked for testing.

Drilling and Completion Techniques for High-Temperature Geothermal Wells

The high temperature formation, strong abrasiveness, numerous fractures and caves are the main problems of high temperature geothermal well drilling, cementing. Cone bit teeth repeated impact tests show that bit life mainly affected by tooth shape, materials, solid tooth technology. Setting special materials around the teeth and adjusting the fitting wring will improve the life of cone bit teeth. Study of quartz sand amount and fineness ratio effect on cement high temperature compressive strength, permeability show that optimization of high temperature cement slurry can improve the high temperature leakage zone cementing sealing and long-term effectiveness.

A Study of the Capability for Fire Resistance of Polypropylene Fibre Concrete

The purpose of this paper is to examine the effect of various polypropylene fibre additions (length and content) to concrete on compressive strength and explosive spalling when subjected to high temperatures, which simulate the building or tunnel fires. The experimental results show that the compressive strength of polypropylene fiber concrete (PFC) and plain concrete decreases with increasing temperature. Fibre content in a certain range has a small effect on the compressive strength of the concrete, therefore the polypropylene (PP) fibers has a great influence on the anti-spalling behavior of concrete under fire loading to ensure the integrity of the structure. Keywords: concrete, polypropylene fibre, high temperature, compressive strength, spalling

Influce Mechanism on Compressive Strength of Coke in Blast Furnace

Coke is the unique role of supporting material column in blast furnace high temperature region. Therefore the most important property is the high temperature compressive strength after reaction. This paper used decarburization electric furnace, electric mirrors, adjustable atmosphere high temperature compression testing machine and other equipments, study on the relationships between coke carbon loss rate and reactivity and size, the distribution rule between high temperature compressive strength and coke carbon loss rate. The study found that the carbon loss rate was affected by reactivity and size, in the same piece of coke, external rate of carbon loss higher than the internal loss, the surface carbon losses affect on coke strength is less, it make coke size decrease; carbon losses occur inside will not affect the size of coke, but it may affect the coke compressive strength seriously. The compressive strength can be divided into two parts: a constant and an amount proportional to carbon loss rate.

EFFECT OF VACUUM INDUCTION MELTING TECHNOLOGY ON MECHANICAL PROPERTIES OF Nb-16Si-22Ti-2Al-2Hf-17Cr ALLOY

This paper dealt with the effect of different induction melting technologies on mechanical properties of Nb -16 Si -22 Ti -2 Al -2 Hf -17 Cr alloy. The cast ingots were fabricated first by arc-melting, and then remolten in the vacuum induction furnace. The results showed that the ingot with refining process of 1800°C/15min and 0.1 at% C addition had finer microstructure and higher room-temperature fracture toughness. In addition, the compressive strength of the ingot with refining technology of 1700°C/10min was 315MPa at 1250°C. However, the arc melting ingot had the lowest fracture toughness and high-temperature compressive strength.