Improvement Of Brittleness Research Articles

A seismic prediction method of reservoir brittleness based on mineral composition and pore structure

The Lucaogou Formation, a typical fine-grained mixed formation in the Jimusaer Sag of the Junggar Basin, exhibits considerable potential for hydrocarbon exploration. Accurate brittle prediction is a crucial factor in determining hydraulic fracturing effectiveness. However, the area features complex lithological characteristics, including carbonate rocks, clastic rocks, volcanic rocks, and gypsum interbeds, along with thin layering and sporadic sweet spots. Traditional prediction methods offer limited resolution and there is an urgent need for a seismic brittle prediction method tailored to this complex geological environment. This paper presents a multi-mineral composition equivalent model for complex lithologies that enables the accurate calculation of Vp and Vs These ratios serve as the foundation for pre-stack elastic parameter predictions, which include Poisson’s ratio and Young’s modulus. By comparing the predicted parameters with well-logging measurements, the prediction accuracy is improved to 82%, with particularly high conformity in intervals characterized by high organic matter and clay content. Additionally, a three-dimensional brittle modeling approach reveals that the brittleness of the reservoir exceeds that of the surrounding rock, showing a gradual improvement in brittleness with increasing burial depth from southeast to northwest. The central area exhibits relatively good brittleness, with a stable, blocky distribution pattern.

Mechanical and wetting properties of 25%NiCr-75%Cr2C3 cermet coated on low carbon steel using HVOF thermal spray technique

The hydrophobic ceramic–metal composites with enhanced mechanical properties will have longer durability because of the embedded liquid-repellent properties, with low water and salt absorption. In this work, the 25%NiCr-75%Cr2C3 cermet powder has been coated on low carbon steel substrate, using High Velocity Oxy-fuel thermal spray technique. The SEM is employed to analyse the morphological characterization of the coating. The mechanical properties of the 25%NiCr-75%Cr2C3 coating is evaluated using the Vickers micro-indentation technique. The micro-hardness, fracture toughness and brittleness index of the coatings are obtained. Also, the wetting property of the coating in 3.5% NaCl salt solution is investigated using the contact angle measured by sessile drop method. The contact angle of the coating is observed to be hydrophobic in nature with a contact angle of 98.14⁰. Thus, 25%NiCr-75%Cr2C3 hydrophobic coatings helps in the improvement of brittleness, fracture toughness, and the microhardness.

Phase stability, brittle-ductile transition, and electronic structures of the TiAl alloying with Fe, Ru, Ge, and Sn: a first-principle investigation.

Phase stability, brittle-ductile transition, and electronic structures of M (M = Fe, Ru, Ge, and Sn) and content change of L10-TiAl (γ-TiAl) and B2-TiAl (β-TiAl) have been investigated using first-principle methods. It is found that M metal atoms preferentially occupy the Al (2e) sites in L10-TiAl and B2-TiAl. According to Pugh's ratio and Poisson's ratio, the brittle-ductile transition is predicted for L10-TiAl and B2-TiAl with Fe, Ru, Ge, and Sn. It is found that the brittle-ductile transition from brittle regions to ductile regions with the transition metal elements Fe and Ru in L10-TiAl and B2-TiAl at the low concentration is approximately from 0 to 6.25at.%. However, the brittle-ductile transition of Ge and Sn at the high concentration approximates from 6.25 to 12.5at.% in L10-TiAl, comparing with B2-TiAl which approximates from 12.5 to 18.75at.%. Electronic structure analysis shows that the improvement of brittleness can be attributed to two factors, including different hybridizations of Al-2p (Ti-3d) orbits with Fe-3d (Ge-4p) and Ru-4d (Sn-5p) orbits and different bandwidths of pseudo-gap. Furthermore, the L10-TiAl and B2-TiAl at low concentration of Fe and Ru can increase the value of ELF, where Ge and Sn atoms become bigger at a high concentration in L10-TiAl and B2-TiAl. At last, elastic constant (Cij), bulk modulus (B), shear modulus (G), and Young's modulus (E) of L10 and B2-TiAl with content change are systematically given.

Plasma-sprayed graphene oxide reinforced alumina composite coatings on low carbon steel with improved fracture toughness, brittleness index, and microhardness

In this work, the mechanical properties of atmospheric plasma-sprayed Al2O3 and Al2O3-xGO (x = 0.5, 1.0, 1.5, and 2.0 wt%) coatings on low carbon steel was evaluated using the Vickers indentation technique, and the effects of GO addition in microhardness brittleness index and fracture toughness were investigated. The Fourier-transform infrared (FTIR) spectroscopy and Field Emission Scanning Electron Microscopy (FE-SEM) techniques were employed to analyze the microstructural characterization of the plasma-sprayed coatings and to confirm the retention of GO in the Al2O3-xGO composite after the plasma spray. It was found that the Vicker’s microhardness of as-sprayed Al2O3 is 4.148 GPa and it decreased with the increase in the addition of GO and for Al2O3-2.0GO, it is 3.305 GPa. The fracture toughness of Al2O3 is 4.86 (MPa m1/2) whereas for Al2O3-2.0GO is 16.85 (MPa m1/2). The fracture toughness has increased whereas the brittleness index has decreased as the weight percentage of GO addition is increased in the Al2O3-GO composite. Thus, the plasma-sprayed Al2O3 and Al2O3-xGO coatings suggest that 2 wt% GO addition helps in the improvement of brittleness, fracture toughness, and the microhardness.

Mechanical properties of artificial materials for bone repair

Bone defect caused by injury, infection, tumor and congenital diseases is one of the most common diseases in clinical orthopaedics. Bone grafts are necessary when self-healing is not effective during the recovery. Preparation of ideal bone substitutes with good biocompatibility and biodegradability to repair bone defects has become the focus. So far artificial materials used in hard tissue repair and reconstruction most notably are metals and their alloys, then the ceramic materials and their composite materials. From the perspective of mechanical properties, metals have some advantages, but corrosion issue and stress shielding of metal have baffled scientists through the age and have been long searched for solution. The elastic modulus of ceramic is more close to the natural bone compared to metal while the improvement of brittleness has been always the emphasis for clinical use. Therefore, development of materials of proper mechanical properties without affecting biological compatibility has become a significant subject.

Microstructural investigation of alumina implanted with 30 keV nitrogen ions

Among ceramics, alumina is being widely used as biomaterials now these days. It is being used as hip joints, tooth roots etc. Ion implantation has been employed to modify its surface without changing it bulk properties. 30 keV nitrogen with varying ion dose ranging from 5 × 10 15 ions/cm 2 to 5 × 10 17 ions/cm 2 is implanted in alumina. Surface morphology has been studied with optical microscope and atomic force microscope (AFM). Improvement in brittleness has been observed with the increase in ion dose. Compound formation and changes in grain size have been studied using X-Ray diffraction (XRD). AlN compound formation is also observed by Fourier transform infrared spectroscopy (FTIR). The change in the grain size is related with the nanohardness and Hall–Petch relationship is verified.

A Study on Improvement of the Properties of Cement Mortar by Admixing Polymer Emulsion and Synthetic Fibers

Studies have been made by various researchers in the attempt to improve the brittleness of cement mortar by admixing polymer emulsion or fibers independently, but the method to admix both polymer emulsion and fiber has not yet been developed.This experiment is based upon the inference that there would be multiple effects by admixing the three components, polymer emulsion, fibers and cement in what is termed a three component system. This was proven by the experiment.In the study of the three component system conducted by the authors, it was found first of all that the sorrounding fibers were remarkably improved in bonding strength with simultaneous improvement in the equilibrium condition of the elasticity between the fibers and the matrices sorrounding the fibers. Consequently the stress distribution of the fibers was remarkably improved. According to these effects, it made it possible for the tensile strength of the fibers to contribute to fully serving the purpose of reinforcement.This experiment suggested one more important way in the improvement of brittleness in hardened cement materials.The present study, while it deals with some fundamental problems in the polymer emulsion-fiber-cement system, aims at its fruition extensively in possible application in the industrial field, giving new outlooks to the studies in this direction.