Characterization of Minerals, Metals and Materials: Characterization of Surface, Thin Films and Coatings
Sponsored by: TMS Extraction and Processing Division, TMS: Materials Characterization Committee
Program Organizers: Jian Li, CanmetMATERIALS; Mingming Zhang, Baowu Ouyeel Co. Ltd; Bowen Li, Michigan Technological University; Sergio Monteiro, Instituto Militar de Engenharia; Shadia Ikhmayies; Yunus Kalay, Middle East Technical University; Jiann-Yang Hwang, Michigan Technological University; Juan Escobedo-Diaz, University of New South Wales; John Carpenter, Los Alamos National Laboratory; Andrew Brown, Devcom Arl Army Research Office
Thursday 8:30 AM
February 27, 2020
Room: 11A
Location: San Diego Convention Ctr
Session Chair: Pasquale Spena, Politecnico di Torino; John Carpenter, Los Alamos National Laboratory
8:30 AM
Fatigue Resistance of Low Pressure Nitrided Cr-Mo Low Alloy Steels: Donato Firrao1; Enrico Morgano2; Graziano Ubertalli1; Angelo Brunelli3; Davide Sabena3; 1Politecnico di Torino; 2Centro Ricerche Fiat; 3Tra.Ind
Fatigue resistance of steel parts can be improved by nitriding, the more the deeper is the layer affected by nitrogen diffusion, as stated by the Lessell-Firrao law. Low-pressure nitriding has been applied to wheel's hubs fabricated with a quenched and tempered Cr-Mo low alloy steel. N diffusion depths have been compared to similar results obtained with the same type of automotive parts subjected to classical gas nitriding. 12 h total low-pressure treatment time provided an almost 100% increase of hardened depth over 40 h gas nitrided parts. Both treatments allowed to reach an adequate fatigue life, whereas induction hardened parts did not. X-ray diffraction analysis provided phase constitution of top converted layers in both nitriding cases. A rationale based on the effect of early treatment stage top layer formation has been developed.
8:50 AM
Unloading Analysis for Indentation Fracture in Molecular Crystals: Alexandra Burch1; John Yeager2; David Bahr1; 1Purdue University; 2Los Alamos National Laboratory
Nanoindentation can be a highly useful resource in characterization of single molecular crystals such as pharmaceuticals and explosives, materials which are often prone to brittle facture. Fracture events during mechanical testing can render results inaccurate and unusable, so it can be helpful to anticipate the fracture behavior of the material under certain loading conditions. For the first time, a technique has been applied to these classes of materials in which nanoindentation is performed with probes of varying acuity, and the resultant unloading traces of the load-depth curves are compared for superimposability or lack thereof. This indicates the occurrence of radial fracture as a result of indentation. This technique has shown that the explosive HMX has an indentation fracture threshold between 4-8 mN, and the pharmaceutical idoxuridine has a threshold between 100-300 mN.
9:10 AM
Growth and Characterization of Metal Nanowhiskers: Gunther Richter1; Wenting Huang1; 1Max Planck Institute for Intelligent Systems
One-dimensional nanostructures attracted in the past years a high interest due to their properties. However, only the metals as one of the oldest were difficult to fabricate in sub-micrometer diameter dimensions. Historically, metal whiskers were produced by recipes originating from Lazarus Ercker’s mining book from 1574. The fundamental principles of these processes were the evaporation of a metal salt, the reduction of said salt in the vapor phase and the condensation of the elemental metal atoms on a usable substrate. We modified this ancient recipe for ultra-high vacuum PVD systems. It is possible grow perfect defect and flaw free nanostructures with diameters of several ten nanometers. Metals with face centered (Cu, Ag, Au, Pd), body centered (Fe), and hexagonal (Co) crystal structure were synthesized successfully as one-dimensional nanowhiskers (NWs) with the new technique. We report our investigations on growth, microstructure and preliminary results on nanowhiskers physical properties.
9:30 AM
Three-Dimensional Characterization of Microstructure and Elemental Segregation of Thermal Spray Coatings: Thomas Ivanoff1; Jonathan Madison1; Nathan Moore1; Aaron Olson1; 1Sandia National Laboratories
Thermal spray coatings are frequently used to provide improved resistance to wear, corrosion and thermal conduction across a variety of structural metals including, but not limited to, steel and nickel. For these reasons, thermal spray coatings have found extensive use in a multitude of industries. The performance and structural integrity of these coatings are often sensitive to microstructure and chemical segregation. Three-dimensional characterization has been used to characterize the complex, interconnected microconstituents in coatings and map chemical inhomogeneity. Here mechanical serial-sectioning of Ta thermal spray coatings is combined with optical and scanning electron microscopy as well as energy-dispersive X-ray spectroscopy to map elemental composition and identify spatial distributions of oxides. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
9:50 AM Break
10:05 AM
Advanced Approach in Investigating the Effects of Hydrogen Trapping on Fish-scaling Resistance of Enameled Steels: Yi Ting Lin1; Hung-Wei Yen1; Lung-Ren Chiang2; 1National Taiwan University; 2Iron and Steel R&D Department, China Steel Corporation
This work aims at developing advanced and new approach in studying hydrogen trapping in interstitial-free (IF) steels with enamel. Unprecedented experimental methods were applied to understand behavior of hydrogen trapping. These methods directly detect hydrogen escape from enameled specimen by thermal desorption analysis (TDA) and permeation test with gas chromatography. Two IF steels with different microstructural design were used to validate their contrast in fish-scaling resistance. Their microstructures were investigated by using optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis (EPMA), and transmission electron microscope (TEM). The results indicated that the conventional TDA or electrochemical permeation test cannot provide appropriate estimation for fish-scaling resistance. Here, the evidence from newly developed methods showed that the enamel layer can serve as effective hydrogen trapping sites to enhanced resistance of fish-scaling.
10:25 AM
A Differential Scanning Calorimetry Study of the Combustion Synthesis of Metal Hexaborides: C. Ingram Vargas Consuelos1; Felix Monge1; Arash Yazdani1; Olivia Graeve1; 1University of California, San Diego
Metal hexaborides present exceptional thermochemical and electrochemical behavior making them suitable for a variety of advanced applications, including electron emission, high temperature coatings, and neutron radiation absorption. The exploration of new techniques to synthesize these materials in an inexpensive and rapid way can result in their use in new advanced applications. Thus, we have explored a new combustion technique for the synthesis of these materials that results in powders of unique cubic morphologies. Aiming to improve the powder morphology and reduce the particle agglomeration, different quantities of LiCl diluent were added to the reactants. The reactant mixture consisted of the relevant metal nitrate, an organic fuel (i.e., carbohydrazide), and the LiCl diluent. Specifically, we present the analysis of the combustion synthesis of LaB6, CeB6, BaB6 and SrB6 by differential scanning calorimetry and thermogravimetric analysis. The resultant products were also investigated by scanning electron microscopy and X-ray diffraction.