In-situ Infrared Research Articles

High thermal safety and conductivity gel polymer electrolyte composed of ionic liquid [EMIM][BF4] and PVDF-HFP for EDLCs

Gel-polymer electrolytes (GPEs) are of great interest to build high-performing rechargeable electrical double-layer capacitors (EDLCs) owing to the combination of good electrochemical properties and improved safety. Herein, we report a quasi-solid-state GPE for EDLCs from a mixture of the poly (vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) and ionic liquid 1-ethyl-3-methylimidazole tetrafluoroborate ([EMIM][BF4]), which avoids the leakage of liquid electrolyte and the low conductivity of common solid electrolyte. The intermolecular forces of GPE was characterized by in-situ infrared (IR) spectroscopy, and the interactions between ionic liquid and polymer were also analyzed. The prepared GPE was observed to be easily procurable, excellent transparency, high thermal safety (thermal stability up to 320 °C) and outstanding electrochemical properties at room temperature (wide electrochemical stability window of 3.91 V versus SS (SS being stainless steel foils) and high ionic conductivity of 6.9 × 10−3 S cm−1). The specific capacitance, the maximum specific energy, and the maximum specific power of the fabricated symmetrical supercapacitor had been determined to be 161.8 F g−1, 89.89 Wh kg−1, and 8 kW kg−1, respectively. Moreover, the EDLC shows extraordinary electrochemical behaviors and cyclic stability over up to 10 000 cycles at 25 °C with 86% capacitance retention under a current load of 2 A g−1. The experimental results indicate the excellent potential of the [EMIM][BF4] ionic-liquid-based gel polymer electrolyte for EDLCs.

Similarity analysis for thermal signature comparison in metal additive manufacturing

Metal additive manufacturing differs from traditional manufacturing processes primarily due to repeated heating and cooling cycles that are inherent to the process. Such cycling leads to different thermal signatures and associated heterogeneities in solidification, solid-state transformation, microstructure, and properties of the printed part. There is, therefore, a need to develop methods to compare thermal signatures in a part with reference to part qualification criteria. In this work, we have developed and demonstrated a similarity analysis procedure to meet this need. Thermal signatures are extracted from in-situ infrared (IR) thermography during a part built using a laser powder bed fusion (l-PBF) machine. Layer-wise variations in thermal signature as a function of part geometry were revealed. Ex-situ microstructure characterization was used to validate the results from similarity analysis. Results and analysis confirmed that our similarity analysis is indeed a useful tool for rapid comparison of thermal signatures, i.e., heterogeneity within the part. Similarity analysis was also useful in identification of anomalous thermal signatures. The analysis method paves the way for deploying in-situ monitoring of AM parts for qualification of AM components.

Competitive adsorption of nitrate, phosphate, and sulfate on amine-modified wheat straw: In-situ infrared spectroscopic and density functional theory study

Amine-modified wheat straw (AMWS) has already been reported as a promising adsorbent for nitrate (NO3) removal due to its cost-effectiveness and high efficiency. However, the NO3 removal mechanism has not been well understood, especially in the presence of co-existing ions. Here, the effect of co-existing anions on NO3 removal by AMWS was investigated and the underlying mechanisms were revealed using a combination of in-situ infrared (IR) spectroscopy and computational modeling. The in-situ IR results indicated that NO3, sulfate (SO4), and phosphate (PO4) are all adsorbed as outer-sphere complexes on AMWS. The two-dimensional-correlation spectroscopy analysis implied the adsorption sequence of SO4 > PO4 > NO3. The adsorption energies obtained from density functional theory calculation range from −0.24 to 0.51 eV (−23.2 to 49.2 kJ/mol), confirming that these anions adsorb on AMWS as outer-sphere complexes. For the first time, this study provides direct spectroscopic evidence of the outer-sphere adsorption of NO3 on AMWS, as well as identifies the adsorption sequence, confirmed by computational modeling. The competitive mechanism of NO3, SO4, and PO4 revealed in this study is helpful to understand and predict the applications of AMWS.

Unity Makes Strength: Constructing Polymeric Catalyst for Selective Synthesis of CO 2 /Epoxide Copolymer

Unity Makes Strength: Constructing Polymeric Catalyst for Selective Synthesis of CO ₂ /Epoxide Copolymer

In-situ infrared cure monitoring combined with two-trace two-dimensional (2T2D) correlation analysis to elucidate the matrix–filler interaction of nanocomposites: Case of thermosetting urethane/silica nanospheres

A novel technique, in-situ infrared (IR) cure monitoring coupled with two-trace two-dimensional (2T2D) correlation analysis, is developed to probe the property-enhancement mechanism of a newly developed thermosetting nanocomposite comprising an acrylic-urethane network (AUN) and silica nanospheres (SNS). The IR spectra were collected in real-time during the curing process at 100 °C. We employ the 2T2D correlation analysis to identify the spectral variations of the interfacial interaction. The curing reaction initially proceeds throughout the sample solution. After the network percolation, the unreacted sites react near the SNS surface and yield additional hydrogen-bonded CO groups that interact with the surface silanol groups. The matrix–filler interactions play a key role in enhancing the hardness and thermal stability of the AUN/SNS nanocomposites by restricting the mobility of the polymer molecules. The proposed technique provides sequential mechanisms in the curing process and a picture of the interfacial interaction for the thermosetting nanocomposite system.

Visualization, understanding, and mitigation of process-induced-membrane irregularities in gas diffusion electrode-based polymer electrolyte membrane fuel cells

Polymer electrolyte membrane fuel cells (PEMFC) show substantial promise for their application in electric vehicles. For large-scale manufacturing of PEMFCs, roll-to-roll coated gas-diffusion-electrodes (GDE) offer certain advantages over other production pathways. Procedures including hot pressing and coating an ionomer overlayer may be necessary for this manufacturing pathway to enable a suitable catalyst layer/membrane interface. The same procedures may potentially introduce membrane irregularities, especially when thin membranes are used. Limited understanding exists regarding if and to what extent such irregularities impact PEMFC performance and lifetime, and therefore be considered defects.In this study, NREL's customized fuel cell hardware that enables quasi in-situ infrared (IR) thermography studies was utilized to visualize spatial hydrogen crossover and identify membrane irregularities that originated from the GDE-based MEA fabrication process. The structure of these membrane irregularities was investigated by scanning electron microscopy (SEM) and its impact on initial H2/air performance was determined. Accelerated stress testing (AST) revealed that these irregularities develop into failure point locations. These results were validated across many MEAs with identified process-induced membrane irregularities. By selecting specific gas diffusion media properties and by fine tuning the MEA hot pressing parameters, the formation of such membrane irregularities was mitigated.

Visualization, Understanding, and Mitigation of Membrane Irregularities in Gas Diffusion Electrode-Based Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) show great promise for their applications in electric vehicles. Most studies on PEMFCs typically use catalyst-coated membranes (CCMs); however, gas-diffusion-electrodes (GDEs) offer advantages for large-scale manufacturing with roll-to-roll coating systems. Additional procedures including hot-pressing and coating a thin ionomer overlayer are necessary in the fabrication process of GDE-based membrane electrode assemblies (MEAs) to improve the otherwise poor catalyst layer/membrane interface.1,2 However, these procedures may also introduce potential irregularities and/or defects, especially when thin membranes are used. Limited understanding exists regarding if and to what extent such irregularities impact PEMFC performance and lifetime.In this study, NREL’s custom fuel cell hardware that enables quasi in-situ infrared (IR) thermography studies3 was utilized to visualize spatial hydrogen crossover in GDE-based MEAs to identify and locate Nafion membrane irregularities. The MEA cross-sectional structure of the membrane irregularity was investigated by scanning electron microscopy (SEM) imaging. The impact of membrane irregularities on open-circuit voltage (OCV), hydrogen crossover and PEMFC initial H2/air performance was systematically studied. The effect of micro-porous layer (MPL) surface roughness of gas diffusion media (GDM) on the membrane irregularity formation mechanism was investigated. By employing GDM with a smoother MPL surface and fine tuning the MEA fabrication process, including compression force and hot-pressing temperature, membrane irregularities were successfully mitigated. Furthermore, IR assisted accelerated stress testing (IR-AST) of MEAs containing different amounts of beginning-of-test membrane irregularities was investigated. These membrane irregularities were demonstrated to be seeds of failure points and dramatically shorten the MEA lifetime. Reference: (1) Wang, M.; Medina, S.; Pfeilsticker, J. R.; Pylypenko, S.; Ulsh, M.; Mauger, S. A. Impact of Microporous Layer Roughness on Gas-Diffusion-Electrode-Based Polymer Electrolyte Membrane Fuel Cell Performance. ACS Appl. Energy Mater. 2019, 2 (11), 7757–7761. https://doi.org/10.1021/acsaem.9b01871.(2) Mauger, S. A.; Pfeilsticker, J. R.; Wang, M.; Medina, S.; Yang-Neyerlin, A. C.; Neyerlin, K. C.; Stetson, C.; Pylypenko, S.; Ulsh, M. Fabrication of High-Performance Gas-Diffusion-Electrode Based Membrane-Electrode Assemblies. J. Power Sources 2020, 450, 227581. https://doi.org/https://doi.org/10.1016/j.jpowsour.2019.227581.(3) Phillips, A.; Ulsh, M.; Neyerlin, K. C.; Porter, J.; Bender, G. Impacts of Electrode Coating Irregularities on Polymer Electrolyte Membrane Fuel Cell Lifetime Using Quasi In-Situ Infrared Thermography and Accelerated Stress Testing. Int. J. Hydrogen Energy 2018, 43 (12), 6390–6399. https://doi.org/https://doi.org/10.1016/j.ijhydene.2018.02.050. Figure 1

Nanomaterial Coating on Micro-Hotplate By EHD Inkjet Printing with in-Site Infrared Laser Heating

Introduction EHD inkjet printing was applied in the fabrication of micro gas sensors recently [1-3]. In most cases, the evaporation of the ink solvent is slow, which makes thickness and uniformity of the film difficult to control. This work introduces an IR laser heating source to the EHD printing system of previous work [2], which accelerates the evaporation of the as-deposited ink solvent on the MHP, so that thick films and even columnar structures can be deposited without the use of special ink solvent.This paper reports a novel in-situ infrared (IR) laser aided electrohydrodynamic (EHD) inkjet printing technique which can deposit hierarchical micro/nano-structured gas-sensitive materials on micro-hotplate (MHP) for micro gas sensor fabrication. Gas-sensitive materials can be deposited quickly on an MHP to form flatten thin film, thick film, and 3D columnar structures. Method The diagram of the printing system is shown in Figure 1. An 808 nm IR laser source with adjustable output power is mounted on the EHD inkjet printing system, focusing at the printing spot with a diameter of about 1 mm. The freestanding MHP with metal electrodes embedded in SiO2 membrane can be heated up to 200oC in seconds by adsorption of the IR power. After EHD printing of the ink onto the 100 µm * 100 µm area of the MHP, the IR laser is turned on with optimized output power and time interval to heat the MHP to a temperature that the solvent evaporated rapidly and the dry gas-sensitive materials are uniformly covered on the surface of the MHP. By repeating the EHD printing and IR heating process, thickness of the film increases regularly and thick film can be prepared. In the preparation of columnar structure, by shrinking the amount of ink droplet and accelerating the IR heating, a tip appears on the surface of the deposited materials. The electric field intensity is larger at the tip since it shortened the distance to the needle, therefore, the electric force drives the ink droplet to deposit on the tip and the tip continues to grow, forming a 3D columnar structure. Results and Conclusions The temperature of the MHP changes with the power of the IR laser in a linear relationship (Figure 2). The flower-like tin oxide powder doped with 3 at% palladium was prepared as the hierarchical-structured gas-sensitive material with a hydrothermal method (Figure 3). The ink was prepared by mixing the powder, DI water and surfactant in a proper proportion, and it was EHD printed on the surface of the MHP (Figure 4). Without IR heating, the solvent did not evaporate completely even after 600 s at room temperature, making it not suitable to print again. By turning on the IR laser with 450 mW for 5 s, the ink was dried and uniform thin film with thickness dfilm<1 µm was coated on the MHP as shown in figure 5 (b). Repeat the printing-heating cycle for 4 times only took 100 s, and thick film of dfilm ≈ 40 µm was obtained as shown in Figure 5 (c). Figure 6 compares the power consumption of the MHP before and after printing, which shows that the MHP with thick gas sensitive film remains good thermal isolation property. The printed 3D columnar structure with height of about 120 µm is shown in figure 5 (d). Increasing the power of the laser can accelerate the evaporation. However, when the IR laser power is more than 500 mW, the droplet on the MHP boil violently and nanomaterials splashes all around.For the first time, the IR aided EHD printing allows the printing of flatten thick gas sensitive film composed of hierarchical-structured nanomaterial on MHP. Also, the technique can further be applied in fabrication of other MEMS devices.This work is supported by the Nature Science Foundation of China (61874018 and 61274076), the Fundamental Research Funds for the Central Universities, and the Nature Science Foundation of Liaoning (20180550923).

Critical S/C Ratio of the Carbon Deposition in the SOFC Anode Using CH4: In-Situ Analysis of the Anode Surface

Surface species on the anode of SOFC using methane was measured by an in-situ infrared (IR) spectroscopy with synchrotron radiation during discharge (S/C (steam-to-carbon) = 0.03) and non-discharge (S/C = 0) modes at SPring-8. The carbon deposition was found in IR spectra during 30 min exposure in CH4 environment in non-discharge mode (S/C = 0). However, the carbon deposition was not found in IR spectra in discharge mode (S/C = 0.03). During measurement, an excess CH4/H2O gas was introduced into the chamber; therefore, H2O remained on the Ni/YSZ surface even at S/C = 0.03, resulting in preventing the carbon deposition through steam reforming reaction. Calculation showed that the carbon deposition occurred when the carbon deposition rate exceeded the reforming rate. It was suggested that a critical S/C ratio, at which the carbon deposition started to occur, was determined from the balance between the carbon deposition and reforming rates.

A statistical learning method for image-based monitoring of the plume signature in laser powder bed fusion

The industrial breakthrough of metal additive manufacturing processes mainly involves highly regulated sectors, e.g., aerospace and healthcare, where both part and process qualification are of paramount importance. Because of this, there is an increasing interest for in-situ monitoring tools able to detect process defects and unstable states since their onset stage during the process itself. In-situ measured quantities can be regarded as “signatures” of the process behaviour and proxies of the final part quality. This study relies on the idea that the by-products of laser powder bed fusion (LPBF) can be used as process signatures to design and implement statistical monitoring methods. In particular, this paper proposes a methodology to monitor the LPBF process via in-situ infrared (IR) video imaging of the plume formed by material evaporation and heating of the surrounding gas. The aspect of the plume naturally changes from one frame to another following the natural dynamics of the process: this yields a multimodal pattern of the plume descriptors that limits the effectiveness of traditional statistical monitoring techniques. To cope with this, a nonparametric control charting scheme is proposed, called K-chart, which allows adapting the alarm threshold to the dynamically varying patterns of the monitored data. A real case study in LPBF of zinc powder is presented to demonstrate the capability of detecting the onset of unstable conditions in the presence of a material that, despite being particularly interesting for biomedical applications, imposes quality challenges in LPBF because of its low melting and boiling points. A comparison analysis is presented to highlight the benefits provided by the proposed approach against competitor methods.

Impacts of electrode coating irregularities on polymer electrolyte membrane fuel cell lifetime using quasi in-situ infrared thermography and accelerated stress testing

In-line quality control diagnostics for roll-to-roll (R2R) manufacturing techniques will play a key role in the future commercialization of the polymer electrolyte membrane fuel cell (PEMFC) used in automotive applications. These diagnostics monitor the fabrication of the membrane electrode assembly (MEA), which detect and flag any non-uniformity that may potentially harm PEMFC performance and/or lifetime. This will require quantitative thresholds and a clear distinction between harmful defects and harmless coating irregularities. Thus, novel fuel cell hardware with quasi in-situ infrared (IR) thermography capabilities is utilized to understand how bare spots in the cathode electrode impact MEA lifetime. An accelerated stress test (AST) simulates chemical and mechanical degradation modes seen in vehicular operation. The actual open circuit voltage and rate of change of this voltage are used as in-situ indicators for MEA failure, enabling capture of the progression of failure point development. Bare spot coating irregularities located at the center of the electrode were found to have no impact on MEA lifetime when compared to a pristine MEA. However, MEA lifetime was found to be considerably shortened when these same irregularities are located at the cathode inlet and, especially, the anode inlet regions of the fuel cell.

Advances in the charging mechanisms for supercapacitor by &amp;lt;italic&amp;gt;in situ&amp;lt;/italic&amp;gt; characterization methods

Supercapacitor is a kind of storage devices that store charge through the electrosorption of ion and fast and reversible faradaic reactions (redox reactions) on the surface of porous electrodes. Recently supercapacitors have boosted its electrochemical properties by tailored porous electrode materials at nanoscale level. Understanding and controlling the storage mechanisms of supercapacitors may hold the key to improving the electrochemical properties of supercapacitor. This article summarizes the advances on charging mechanisms of supercapacitors using various in-situ experimental techniques, including in-situ NMR spectroscopy, electrochemical quartz crystal microbalance (EQCM), in-situ infrared (IR) spectroscopy and in-situ scattering approaches. Finally, future research directions in advanced characterization techniques for supercapacitor are briefly discussed.

Desorption mechanisms of phosphate from ferrihydrite and goethite surfaces

The fate of phosphate in the environment is governed by reactions at particle surfaces. These adsorption and desorption reactions display biphasic kinetics involving an initial rapid reaction followed by a substantially slower one extending over long time periods. In this study we have investigated the molecular mechanisms of desorption kinetics of phosphate from ferrihydrite and goethite nanoparticles in the absence of competing ligands. Desorption was studied by means of in-situ infrared (IR) spectroscopy over a wide pH range and a time period of 24h. The spectroscopic data sets were subjected to multivariate curve resolution alternating least squares (MCR-ALS), which enabled the resolution of surface species characterized by unique IR spectra together with their corresponding kinetic profiles. The desorption results showed the typical biphasic behavior and that increasing positive surface charge of ferrihydrite and goethite slowed down desorption of the negatively charged phosphate ions. Moreover, diprotonated phosphate desorbed faster than monoprotonated phosphate at a given pH. At circumneutral pH values desorption from ferrihydrite was substantially faster as compared to goethite, and this could be ascribed to electrostatic effects and differences in charging between ferrihydrite and goethite. The collective desorption results were explained by a model, consisting of a series monodentate phosphate surface complexes in different protonation states, in conjunction with a description that accounts for the electrostatic effects on desorption kinetics at charged mineral-water interfaces. The fast and slow desorption followed directly from this model and indicated that biphasic kinetics can be caused by a single phosphate surface complex as a result of decreasing surface coverage along with the lateral repulsive interactions between adsorbed phosphate groups. Hence, in contrast to previous models our study has shown that biphasic desorption kinetics do not have to involve several different structural complexes related to either weak and strong sites or a distribution of phosphate between external surfaces and mineral pores.

Methanol formation by CO2 hydrogenation on Au/ZnO catalysts – Effect of total pressure and influence of CO on the reaction characteristics

As part of concepts for chemical energy storage of excess electrical energy produced from renewable sources, we have investigated the performance of a Au/ZnO catalyst for the formation of methanol from CO2 and H2 at pressures between 5 and 50bar and at 240°C, focusing on the effect of total pressure and on the influence of CO, and compared it to the activity and selectivity of commercial Cu/ZnO/Al2O3 catalysts. Kinetic measurements reveal that Au/ZnO catalysts have similar methanol formation rates and superior selectivity toward methanol compared to Cu/ZnO/Al2O3 over the whole range of pressure. CO, which can be formed during CO2 hydrogenation via the reverse water–gas shift (RWGS) reaction, has little effect on the methanol formation for low CO concentrations up to 1%, while higher CO concentrations significantly diminish the methanol formation rate, at constant CO2 and H2 partial pressures. From these kinetic data and from additional in-situ infrared (IR) spectroscopy measurements, performed during CO2 hydrogenation as well as during CO hydrogenation at 5bar, we conclude that methanol formation from CO2 and CO proceeds via different, independent reaction pathways and therefore CO is not an intermediate in the hydrogenation of CO2. Consequences of these results on possible applications of Au/ZnO in renewable energy concepts will be discussed.

Synthesis of lithium nickel cobalt manganese oxide cathode materials by infrared induction heating

This study adopts an in-situ infrared (IR) sintering incorporated with carbonization technique to synthesize carbon-coated LiNi1/3Co1/3Mn1/3O2 (LNCM) cathode materials for Li-ion batteries. Compared with electric resistance heating, the in-situ IR sintering is capable of rapidly producing highly-crystalline LNCM powders at 900 °C within a short period, i.e., 3 h in this case. Glucose additive is employed to serve a carbon precursor, which is carbonized and coated over the surface of LNCM crystals during the IR sintering process. The electrochemical performance of LNCM cathodes is well examined by charge–discharge cycling at 0.1−5C. An appropriate carbon coating is capable of raising discharge capacity (i.e., 181.5 mAh g−1 at 0.1C), rate capability (i.e., 75.0 mAh g−1 at 5C), and cycling stability (i.e., capacity retention: 94.2% at 1C after 50 cycles) of LNCM cathodes. This enhanced performance can be ascribed to the carbon coating onto the external surface of LNCM powders, creating an outer circuit of charge-transfer pathway and preventing cathode corrosion from direct contact to the electrolyte. Accordingly, the in-situ IR sintering technique offers a potential feasibility for synthesizing cathode materials commercially in large scale.

BioRef – a time-of-flight neutron reflectometer combined with in-situ infrared spectroscopy at the Helmholtz Centre Berlin

The novel BioRef reflectometer currently under construction in neutron guidehall-I of the BER-2 reactor at the Helmholtz Centre Berlin is designed for applications in soft matter science at solid-liquid interfaces especially under dynamic conditions. In addition to a time-of-flight (TOF) approach to be realised with three choppers in order to adapt resolutions and wavelength bands to the needs of specific applications, the instrument will be equipped with an in-situ infrared (IR) spectrometer operating in its surface sensitive ATR-geometry for simultaneous spectroscopic and conformational studies. The instrument will become operational in 2010.

In‐situ Flow‐Cell IRAS Observation of Intermediates during Methanol Oxidation on Low‐Index Platinum Surfaces

Structural effects on intermediate species of methanol oxidation are studied on low-index planes of platinum using in-situ infrared (IR) spectroscopy. A flow cell is designed for rapid migration of reactant and product species on the electrode surface. IR spectra show adsorption of formate and the formation of carbonate species on the Pt(111) surface at potentials higher than that of CO oxidation. The band assignments for carbonate and formate are confirmed by vibrational isotope shifts. On Pt(100), the absorption band of adsorbed formate is much smaller than that on Pt(111). On the other hand, there is no adsorbed formate on Pt(110) in the potential region examined. The band intensity of formate follows the order: Pt(111)>Pt(100)>Pt(110). This order is opposite to that of the current density in the regions of higher potential. Adsorbed formate on Pt(111) behaves like a catalyst-poisoning intermediate, like adsorbed CO.

Metal Carbonyl Cluster Synthesis in Nanocages: Spectroscopic Evidence of Intermediates in the Formation of Ir4(CO)12in Zeolite NaY

The assembly of Ir4(CO)12 from Ir(CO)2(acac) precursors in the supercages of zeolite NaY was investigated by extended X-ray absorption fine structure (EXAFS) and in-situ infrared (IR) spectroscopies. The data show that the conditions of pretreatment of the zeolite significantly affect the formation process of Ir4(CO)12. When the zeolite was initially largely dehydrated, so that the precursor molecules were well dispersed in the zeolite cages, dimeric intermediates in the formation of Ir4(CO)12 (approximated as Ir2(CO)8) were observed by both IR and EXAFS spectroscopies. In contrast, when the zeolite initially contained a substantial amount of water, the resultant Ir4 clusters were formed faster than those in dehydrated zeolite, and evidence of intermediates was not observed. The results show how synthesis in the confined spaces of the zeolite nanoporesin the absence of solventsaffords opportunities to control and elucidate the chemistry, different from that in solution.

In-Situ Infrared (IR) Detection and Heating of the High Pressure Phase of Silicon during Scratching Test

ABSTRACTA novel method of in-situ detection of the high pressure phase transformation of silicon during dead-load scratching is described. The method is based on the simple fact that single crystal silicon is transparent to Infrared light while metallic materials are not. Infrared heating during scratching has been performed to thermally soften and deform the transformed metallic material and some promising results were obtained. The sample material used here is silicon, but the same approach can be applied to germanium and other materials, such as ceramics (SiC), which have appropriate optical properties.

In-Situ Infrared (IR) Detection and Heating of the High Pressure Phase of Silicon during Scratching Test

ABSTRACTA novel method of in-situ detection of the high pressure phase transformation of silicon during dead-load scratching is described. The method is based on the simple fact that single crystal silicon is transparent to Infrared light while metallic materials are not. Infrared heating during scratching has been performed to thermally soften and deform the transformed metallic material and some promising results were obtained. The sample material used here is silicon, but the same approach can be applied to germanium and other materials, such as ceramics (SiC), which have appropriate optical properties.