Material Characterization

Material characterization, Physical Property Testing, and Microstructural CharacterizationAll materials are made up of atoms of various elements from periodic table. More often materials are made up of more than one type of atoms. Materials are generally classified in to organic and inorganic materials. Some simple examples of organic materials are plastics, polymers, bio polymers, coal, crude oil, etc. Common examples of inorganic materials are metals, alloys, ceramics, glass, concrete, etc. They are also classified as amorphous, crystalline materials based on the fundamental arrangement of atoms that make up the materials.

Material characterization involves a broad group of analytical procedures used to evaluate chemical and physical make up of any materials. It is different from material testing in that it focusses on fundamental characteristics rather than applied or utility properties. Simple example is chemical analysis of materials to identify the chemical elements or molecules involved in the constitution of a material. Physical characterization involves measuring physical properties and microstructure, etc.

At Touchstone Testing Laboratory, we offer the following services.

  • Physical Property Testing
  • Microstructural Characterization
  • Chemical Analysis

Physical Property Testing

Physical properties of materials encompass a wide range of properties that can be classified in to volumetric properties, thermal properties, electrical properties, etc. Major volumetric properties are specific gravity, density, viscosity, surface tension, etc. Included in the thermal properties are thermal conductivity, thermal expansion, phase change temperatures, etc., while electrical properties include mainly bulk and surface electrical conductivity. These properties along with mechanical and chemical properties are needed for selection, design and manufacturing of products and components.

Capability – At touchstone testing laboratory we have equipment and capability to measure the following physical properties

  • Density measurements of mainly solids using Archimedes principle
  • Apparent density of bulk and porous solids
  • Viscosity measurements of some low viscosity liquids using torsionalpendulum
  • Coefficient of linear thermal expansion of solids by dilatometry
  • Phase change measurements using differential scanning calorimetry and dilatometry
  • Mass change as a function of heat input by thermogravimetry
  • Electrical conductivity of solids
  • Thermal conductivity of solids

Some relevant standards:

  • ASTM B193 – Standard Test Method for Resistivity of Electrical Conductor Material
  • ASTM C693 – Standard Test Method for Density of Glass by Buoyancy
  • ASTM C559 -Standard Test Method for Bulk Density by Physical Measurements of Manufactured Carbon and Graphite Article
  • ASTM C830 – Standard Test Method for Bulk Density by Physical Measurements of Manufactured Carbon and Graphite Articles
  • ASTM C838 – Standard Test Method for Bulk Density of As-Manufactured Carbon and Graphite Shapes
  • ASTM D257 – Standard Test Methods for DC Resistance or Conductance of Insulating Material
  • ASTM D792 – Standard Test Methods for Density and Specific Gravity (Relative Density) ofPlastics by Displacement
  • ASTM D1505 – Standard Test Method for Density of Plastics by the Density-GradientTechnique
  • ASTM E228 – Standard Test Method for Linear Thermal Expansion of Solid Materials with a Push-Rod Dilatometer
  • ASTM E3116 – Standard Test Method for Viscosity Measurement Validation of RotationalViscometers

Microstructural Characterization

Fundamental building blocks of materials are atoms. In solids and to some extant in liquids, atoms are generally arranged in to what are called crystals in a repetitive manner. A simple example is the common salt, sodium chloride, where sodium and chlorine atoms are arranged alternatively at the corners of a simple cube. The distance between the sodium and chlorine atoms is determined by the interatomic attractive and repulsive forces. Several different types of crystalline motifs are available for materials depending on the type of atoms involved. Basic crystal motifs are cubic, hexagonal, tetragonal, orthorhombic, monoclinic and triclinic forms. Further materials will contain what are called grains with each grain containing repetitive patterns of atoms in one of the above crystalline motif. Thus, materials are also called poly crystalline materials. Most engineering materials in addition will also have additional matter, also called second phase, like impurities in the form of inclusions, etc. Often these second phases may also contribute to the property of the material. Thus, materials are in general poly crystalline poly phase. Microstructural characterization involves identifying, measuring size and shapes of these grains and phases.

Capability – At Touchstone testing laboratory we routinely carry out microstructural characterization of metallic, polymeric, ceramic materials and composites for aerospace, automotive, power generation OEMs as well as material and composite manufacturers. We have analyzed microstructures of variety of ferrous products like carbon steel, stainless steel, interstitial free steels, regular and alloy cast irons, etc. We have also extensive experience in analyzing nonferrous materials like aluminum, aluminum alloys, copper, brass, bronze, and exotic materials nickel, chromium, niobium, tungsten-based alloy systems and PGM materials. We can analyze also fiber materials like carbon, glass, ceramic as well as metal fibers and natural fibers. We have capability to analyze dust particles like soot, silica, etc., and powder metals. Following facilities are available for materials characterizations.

  • Fully equipped specimen preparation laboratory for cutting, mounting, polishing samples andproducts
  • Optical (reflective and transmission) microscopes using regular white light and polarized light.
  • Fluorescence microscope
  • Stereo optical reflection microscope for three-dimensional imaging of fracture surfaces andstructural analysis
  • Scanning electron microscope for high resolution and high magnification imaging of metallic,polymeric, and ceramic materials
  • Quantitative microcopy tools
  • X-ray unit for powder diffraction

Some relevant standards:

  • ASTM E3 – Standard Guide for Preparation of Metallographic Specimens
  • ASTM E112 – Standard Test Methods for Determining Average Grain Size
  • ASTM E340 – Standard Practice for Macro Etching Metals and Alloys
  • ASTM E381 – Standard Method of Macro etch Testing Steel Bars, Billets, Blooms, etc.
  • ASTM E407 – Standard Practice for Micro Etching Metals and Alloys
  • ASTM E1558 – Standard Guide for Electrolytic Polishing of Metallographic Specimens
  • ASTM E2015 – Standard Guide for Preparation of Plastics and Polymeric Specimens forMicrostructural Examination
  • ASTM E2228 – Standard Guide for Microscopic Examination of Textile Fibers
  • ASTM F1877 – Standard Practice for Characterization of Particles

Chemical Analysis

Fundamental building blocks of observable materials are atoms and molecules. Properties of materials depend on how these atoms and molecules combine and interact with each other. Chemical analysis is a way to understand the constitution of materials in terms of atoms and combinations of them.

Many different techniques are available to analyze the chemistry of materials. These are generally classified in to wet and dry chemical analysis. Wet method involves basically dissolving the materials in acids or alkali solutions and titrating the solutions against standards. Alternative is to use dry methods where the materials are irradiated using high energy radiations like X rays, g rays, lasers, etc., as well as particle beams like electrons, neutrons, etc., and the response is analyzed through techniques like spectroscopy.

Capability – At Touchstone testing laboratory, we have limited capability to analyze samples chemically. We use electron beams in an electron microscope to generate x rays which are then analyzed for the content semi quantitively. We also have inductively coupled plasma unit to analyze chemistry of metallic samples like aluminum alloys.

Some relevant standards:

  • ASTM A751 – Standard Test Methods, Practices, and Terminology for Chemical Analysis of Steel Product
  • ASTM E415 – Standard Test Method for Analysis of Carbon and Low-Alloy Steel by Spark Atomic Emission Spectrometry
  • ASTM E1251 – Standard Test Method for Analysis of Aluminum and Aluminum Alloys bySpark Atomic Emission Spectrometry
  • ASTM E1505 – Standard Guide for Quantitative Analysis by Energy-Dispersive Spectroscopy
1094 Middle Creek Road
   Triadelphia, WV 26059

304-907-4010

info@touchstonetesting.com

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