**4. Characterization techniques**

Different phases in the HCFC slag are identifies using X-ray diffraction technique. Essentially, the phases are determined by qualitative analysis of the phases through JCPD file. For this purpose, ferrochrome slags powdered are dried 110°C for 24 h and crushed into fine powdered use in the examination. For analysis purpose a Phillips PW-1710 Advance wide-angle X-ray diffractometer and Phillips PW-1729 X-ray generator using CuKα radiation (wavelength, λ = 0.154 nm). The generator is operated at 40 kV and 20 mA. The powder samples are placed on a quartz sample holder at room temperature and are scanned at diffraction angle 2θ from 10° to 60° at the scanning rate of 5°/min. X-rays diffraction studies are made with treated GP samples at different stages of curing. Similar analyses are also made with the as received HCFC slag for comparison purpose.

FTIR technique is used to analyze the presence of functional groups, formation of chemical linkage using a FTIR spectrometer (Nexus-870, Thermo Nicolet spectrophotometer) in range of 400–4000 cm−1. The instrument parameters are kept constant (50 scan at 4 cm−1 resolution, absorbance mode). In this spectrometer, the IR radiations from an IR source are passed through the sample and the amount of energy adsorbed is recorded by suitable detector and is guided through an interferometer where a Fourier Transform is performed on the output signal. The pellet (13 mm diameter, 0.3 mm thick) so prepared is used for IR characterization. Before running the samples, a background spectrum is collected. Then pellets samples are put in a sample holder. The pellets are exposed to IR radiation in the spectrometer and data were collected.

Surface morphologies of prepared materials are analyzed by electron microscope (SEM using Carl Zeiss Supra 40). SEM is a microscope that uses electrons in place of light to produce image. In this measurement, the electron beam produced from electron gun is focused on a small portion of the sample that is kept in vacuum. Detector collects the output signals during the interaction of electrons with the sample and that is sent to a computer. This forms the final image. Special preparation technique is needed for the sample to avoid moisture absorption. All nonconducting materials need thin layer of conducting coating. This is done by 'sputter coater'. Operating voltage was 4 kV. The sample is placed in a small vacuum chamber. The argon gas is ionized in the applied electric field to form argon ion (Ar+ ). The argon ions knock gold atoms from the surface of the gold foil and get deposited on sample. The elemental analyses are carried out with the help of EDX attached to the microscope.

TGA analysis is a type of thermal analysis that measures mass change of materials with change of temperature. The purpose of doing such experiment is to measure volatile content, thermal stability, degradation characteristics, etc. The asprepared fine powdered of HCFC slag for Geopolymer preparation and as-prepared cured Geopolymer materials are also run in a thermogravimetric (TG) analyzer Perkin Elmer Pyris Diamond analyzer. Heating rate is taken 10°C/min during the experiments and is performed in an inert atmosphere (N2 gas). The TGA run is carried out in the temperature range of 50–300°C.

Differential scanning calorimetry (DSC) is a technique for measuring the energy necessary to establish a nearly zero temperature difference between a substance and an inert reference material, as the two specimens are subjected to identical temperature regimes in an environment heated or cooled at a controlled rate. The technique provides qualitative and quantitative information about physical and chemical changes that involve endothermic or exothermic processes or changes in heat capacity using minimal amounts of sample. It has many advantages including fast analysis time, typically thirty minutes, easy sample preparation, applicability to both liquids and solids, a wide range of temperature applicability and excellent quantitative capability.

DSC has been used in the evaluation of small transitions such as multiple phase transitions in liquid crystals and those due to side chains in polymers which cannot be resolved by most other techniques. It allows accurate determination of temperatures associated with thermal events. Temperature can be calibrated with respect to one or more standards which allow highly accurate, precise and reproducible values. The technique reveals the thermal history imparted to thermoplastics as a result of different processing conditions. The information generated can be used to vary heating rates to deliver the required degree of crystallinity. Differential scanning calorimetry (DSC, Perkin Elmer Pyris Diamond) was used for determination of crystallization. Samples (5–10 mg) were placed in sealed aluminum pans and scanned under a constant nitrogen purge (20 mL/min). Subsequently, the samples were heated from 50–300°C at a rate of 10°C/min, cooled to 30°C at the same rate and held for 2 min to stabilize. Finally a second scan was carried out from room temp to 300°C. The result of enthalpy was noted from the second scan. DSC study is made for measurement of enthalpy of the two materials *i.e.*, as-received HCFC slag and GP prepared with HCFC slag. The test is carried out in nitrogen environment (N2).

Tests to obtain the stress–strain curves prepared HCFC slag based GP in compression are performed using an Ultimate Tensile machine (UTM), AIMIL *Synthesis and Characterizations of High Carbon Ferrochrome (HCFC) Slag Based Geopolymer DOI: http://dx.doi.org/10.5772/intechopen.97140*

COMPTEST 2000 model and is determined by standard ASTM which is inbuilt in the UTM machine. The tests on 100 × 200 mm GP cylinders are performed by using the displacement-control mode available in the test machine. It took approximately 30 to 60 minutes to complete each test in order to obtain the stress–strain curve(s). Loading in compression over a period is found to cause reduction in the measured value of the compressive strength of test cylinders. Maximum load is taken at the point of fracture of the sample. The specimen(s) is demoulded compression testing.
