Missouri University of Science and Technology

About: Missouri University of Science and Technology is a education organization based out in Rolla, Missouri, United States. It is known for research contribution in the topics: Artificial neural network & Control theory. The organization has 9380 authors who have published 21161 publications receiving 462544 citations. The organization is also known as: Missouri S&T & University of Missouri–Rolla.

Strength of Zirconium Diboride to 2300°C

Abstract: The strength of zirconium diboride (ZrB2) ceramics was measured up to 2300°C, which are the first reported measurements above 1500°C since 1970. ZrB2 ceramics were prepared from commercially available powder by hot pressing. A mechanical testing apparatus capable of testing material in the ultra-high temperature regime with atmosphere control was built, evaluated, and used. Four-point bend strength was measured as a function of temperature up to 1600°C in air and between 1500°C and 2300°C in argon. Strength between room temperature and 1200°C was ~390 MPa, decreasing to a minimum of ~170 MPa between 1400°C and 1500°C, with strength increasing to ~220 MPa between 1600°C and 2300°C.

Low-Energy Electrons and Their Dynamical Correlation with Recoil Ions for Single Ionization of Helium by Fast, Heavy-Ion Impact.

Abstract: Helium single ionization by 3.6 meV/u Ni[sup 24+] impact was explored in a kinematically complete experiment by combining a high-resolution recoil-ion momentum spectrometer with a novel 4[pi] low-energy electron analyzer. More than 90% of the soft electrons'' ([ital E][sub [ital e]][approx lt]50 eV) are ejected in the forward direction in agreement with classical-trajectory Monte Carlo predictions. The electron longitudinal momentum is not balanced by the longitudinal momentum change of the projectile but mainly by the backwards recoiling He[sup 1+] ion. Energy losses of the 0.2 GeV projectiles as small as [Delta][ital E][sub [ital P]]/[ital E][sub [ital P]]=3.4[times]10[sup [minus]7] are observable.

Multi-scale investigation of microstructure, fiber pullout behavior, and mechanical properties of ultra-high performance concrete with nano-CaCO3 particles

Abstract: The mechanical properties of a fiber-reinforced concrete are closely related to the properties of the matrix, fiber, and fiber-matrix interface. The fiber-matrix bond property is mainly governed by the adhesion between the fiber and surrounding cement materials, as well as the strength of materials at the interfacial transition zone. In this paper, the effect of nano-CaCO3 content, varying between 0 and 6.4%, by mass of cementitious materials, on microstructure development, fiber-matrix interfacial bond properties, and mechanical properties of ultra-high performance concrete (UHPC) reinforced with 2% steel fibers were investigated. The bond properties, including bond strength and pullout energy, were evaluated. Mercury intrusion porosimetry (MIP), backscattered electron microscopy (BSEM), optical microscopy, and micro-hardness testing were used to characterize the microstructure of matrix and/or interfacial transition zone (ITZ) around an embedded steel fiber. Test results indicated that the incorporation of 3.2% nano-CaCO3 significantly improved the fiber-matrix bond properties and the flexural properties of UHPC. This was attributed to densification and strength enhancement of ITZ as observed from micro-structural analyses. Beyond the nano-CaCO3 content of 3.2%, the fiber bond and mechanical properties of UHPC decreased due to increased porosity associated with agglomeration of the nano-CaCO3.

Crystallization Kinetics of a Lithia–Silica Glass: Effect of Sample Characteristics and Thermal Analysis Measurement Techniques

Abstract: DTA and both isothermal and nonisothermal DSC techniques are presently used to investigate the crystallization kinetics of a 40 (mol) percent Li2O-60 percent SiO2 glass as a function of glass powder particle size, the use of either alumina or Pt as the crucible material, the use of N, O, or Ar atmospheres, and surface pretreatments of the glass powder with deionized water, HCl, or HF. Neither the furnace atmosphere nor the crucible material had a significant effect on activation energy, frequency factor, or Avrami exponent. Washings of the glass with the three different fluids decreased the crystallization temperature by 25 to 30 C.