CARBON / SULFUR ANALYZER
Due to difficulties in getting Carbon and Sulfur into solution, these elements are not readily measured by ICP Spectroscopy and an alternative technique is needed. The LECO CS-300 combustion analyzer is used for the measurement of Carbon and Sulfur in metals, ores, ceramic and other inorganic materials. The sample is combusted in a stream of purified Oxygen which produces CO2 and SO2 from the Carbon and Sulfur, respectively. These species are then detected and quantified by infrared detection. The instrument is capable of detecting Carbon and Sulfur down to approximately 0.005% by weight in a metal sample. Standards are run with each sample which have a Carbon and Sulfur content as close to the sample as possible.
DIFFERENTIAL SCANNING CALORIMETER (DSC)
A Differential Scanning Calorimeter (DSC) is an instrument which accurately measures the heat absorbed or given off from a sample as a function of temperature. Such thermal parameters as the Glass Transition Temperature (TG) (which is the temperature at which a glassy material begins to flow), the melting temperature, and the enthalpy of melting can all be measured by DSC. Our main interest will be the melting temperatures and glass transitions of polymer samples, however, the DSC can measure thermal properties for crystalline organic compounds and liquids as well. DSC data is most often used in conjunction with TGA data (which gives weight loss as a function of temperature) and FTIR data, which provides the identity of a polymer sample. Such thermal parameters as the glass transition, melting point, and decomposition temperature are useful to engineers who must select polymers to withstand a given thermal environment.
FTIR SPECTROSCOPY, MICRO & BENCH TECHNIQUES
FTIR is a spectroscopic technique in which infrared light is passed through a sample, which has the characteristic adsorption frequencies in the infrared region. This produces an infrared spectrum which looks like a series of peaks and valleys on an X/Y graph. This spectrum is unique for a given organic material and can be thought of as the materials chemical fingerprint. This technique is useful both for routine material verification/identification of polymers and identification of trace contaminates via the FTIR Microscope. Micro-FTIR spectroscopy is performed on a Bio-Rad UMA-250 microscope which is capable of obtaining spectra of objects down to about 25 microns in size. Micro-FTIR is widely used for identification of trace contaminates on manufactured items.
GLOW DISCHARGE SPECTROMETER (GDS)
Glow Discharge Spectrometer (GDS) is used to measure elemental concentrations in solid materials. In the analysis Argon Ions mill material from the sample surface. This milled or sputtered material is then excited in a plasma discharge, and the resulting light emission is used to quantify the composition of the sample. Because the surface of the sample is sputtered uniformly, GDS can analyze samples that can not be analyzed using traditional spark spectroscopy.
NHML currently has the following methods and standards available for the GDS:
Carbon & Alloy Steels
HARDNESS & MICROHARDNESS TESTERS
New Hampshire Materials Lab specializes in hardness testing of incoming materials and finished products. Materials tested include metals and alloys, polymers, ceramics, and composites. Hardness tests include Rockwell, Knoop, Vickers, Durometer, and Barcol.
Microhardness (Knoop and Vickers)
Microhardness testing is typically used for parts, wire, and foil samples that are too small or too thin for conventional hardness testing. This testing uses low loads, typically 10 to 1000 grams. A highly polished, pyramid shaped diamond is used as an indenter. The diamond may be a rhombic based pyramid (Knoop microhardness) or a square based pyramid (Vickers microhardness). With Knoop microhardness tests, the depth of penetration of the indenter is about 1/30th of the length of the indentation produced.
Both hardness scales are based on formulas that include the load used and the indentation length produced by the test, which are typically are in lengths between 20 and 200 micrometers. With a given load, the Vickers indenter penetrates roughly twice as far into the material being tested when compared with the Knoop indenter. Accordingly, the Vickers tests are less sensitive to small differences in the surface condition.
Accurate measurement of either the Vickers or the Knoop indentation requires a good surface finish that results from standard metallographic grinding and polishing sequences. The smaller the indentation, the more critical the surface finish becomes. Furthermore, the hardness number determined in the microhardness tests is load dependent. This load dependency occurs with loads of 500 gf or less for Knoop hardness values and loads of 100 gf or less for Vickers hardness values. In most cases, the apparent Knoop microhardness decreases with increasing load while the apparent Vickers hardness increases with increasing loads.
In ICP Spectroscopy samples are acid digested and diluted in water and aspirated into a plasma torch. The emitted light is then measured and quantified relative to known standards. ICP is a very versatile spectroscopic technique, capable of analyzing a full spectrum of samples from water samples to dissolved alloys of Steel, Aluminum, Brass, Titanium and Nickel based alloys. ICP Spectroscopy is used to accurately determine the chemical composition of ferrous and nonferrous alloys as well as a variety of other samples and extracts. Our lab currently uses a Prism ICP from Teledyne Leeman Labs. The standards used for analyses are traceable to NIST.
MECHANICAL TESTING SYSTEM
Our universal testing machines are capable of tensile and compression testing modes within a single frame. Test types may include tensile, compression, shear, flexure, peel, tear, cyclic, and bend tests.
SCANNING ELECTRON MICROSCOPY (SEM) / ENERGY DISPERSIVE SPECTROSCOPY (EDS)
Scanning Electron Microscopy allows detailed surface analysis as well as high magnification viewing of very small features. The Energy Dispersive Spectroscopy (EDS) feature allows the additional advantage of being able to obtain the elemental composition of small objects or surfaces. Also of particular use is when this technique is used in conjunction with Micro-FTIR for the characterization of trace contaminants and unknowns.