Vickers Microhardness Studies Research Articles

Directional growth of 2-ethylimidazolium d-tartrate crystal along (001) and investigation of optical properties for optical limiting applications

A single crystal of 2-Ethylimidazolium d-Tartrate (2EIMDT) was grown along the preferred direction of (001) by the Sankaranarayanan-Ramasamy method. The growth direction was confirmed by X-ray Diffraction analysis. The optical homogeneity and the defect analysis of the grown crystal were carried out using birefringence interferometry, Williamson-Hall plot, and chemical etching. They revealed that the grown crystal possesses good optical and crystalline quality. Using the optical transmission spectrum, the optical band gap and Urbach energy were estimated to be 5.1 eV and 140 meV, respectively. The temperature dependence of the refractive index and thermo-optic coefficient were measured using the prism coupling technique for different wavelengths. The thermo-optic coefficient was found to be negative with values ∼10−5/°C. The laser damage threshold was estimated to be 6.5 GW/cm2 for a 1064 nm laser. Vickers micro-hardness study revealed that the (001) plane of the crystal is characterized by Meyer's index of 1.93. From the Z-scan measurement, it was found that the grown crystal exhibits two-photon absorption characteristics and the obtained imaginary parts of the third-order nonlinear optical (TONLO) susceptibility is 1.95 × 10−14 esu. Additionally, the onset optical limiting threshold was estimated to be 3.89 × 1012 W/m2 which indicates the potential of 2EIMDT for optical limiting applications.

Novel third order nonlinear optical stilbazolium crystal replaced with 3-methoxy benzaldehyde as donor for optical device applications

A novel organic nonlinear optical stilbazolium group single crystal of 1-methyl-2-[2-(3-methoxystyryl)]-pyridinium iodide (subsequently referred to as MSMI) was grown by the solution growth technique using the method of slow evaporation at ambient temperature. The Single-crystal XRD investigation indicates that the MSMI crystal belongs to a monoclinic crystal system with a centrosymmetric space group. CHN elemental analyser confirms the weight percentage of carbon (C = 51.00 %) hydrogen (H = 4.55 %) and nitrogen (N = 3.94 %) in the MSMI crystal structure. The presence of 16 hydrogen atoms and 15 carbon atoms in the MSMI was affirmed by the Nuclear Magnetic Resonance (NMR) spectroscopic analysis. Fourier Transform Infrared (FTIR) studies confirmed the fundamental vibrations for different functional groups found in the MSMI crystal. The Hirsfeld surface analysis figured out the hydrogen bond interaction and π…π interaction which supports the stability of the crystal structure. The crystal is found to exhibit transmittance of wavelength above 400 nm and has a band gap of 3.05 eV ascertained from UV–Vis-NIR spectroscopic analysis. Photoluminescence (PL) studies reveal that the title crystal has an emission wavelength of 572 nm. The surface characteristics of the title crystal were examined by Atomic Force Microscopy (AFM), and etching studies. The value of Meyer's number is n = 1.8 which is determined by the Vickers microhardness studies. The value of the third-order nonlinear refractive index (n2) is 4.662×10−8 cm2/W, the nonlinear absorption coefficient (β) is 1.305×10−3 cm/W, nonlinear susceptibility (χ(3)) is 9.297×10−5 esu and the optical limiting threshold is 11.43 J/cm2 was ascertained form the Z-scan technique. The results indicate that the MSMI crystal is a potential optical limiter and has promising applications in nonlinear optical devices.

Investigations on theoretical models describing the load-indentation size dependence for (001), (010), (101), (1̄1̄1) and (1̄11) faces of triglycine sulphate

Ferroelectric triglycine sulphate (TGS) single crystals were grown by slow evaporation technique over a period of 30–40 days. The Vickers microhardness studies have been carried out on (001), (010), (101), ([Formula: see text][Formula: see text]1) and ([Formula: see text]11) faces of the TGS crystal. The as-grown (001) face and (010) face with the ferroelectric phase were used to study the temperature dependence of hardness. The indentation size effect (ISE) described using the five theoretical models viz., Meyer’s law, Hays–Kendall, elastic/plastic deformation (EPD), proportional specimen resistance (PSR) and modified PSR model has been investigated on all the crystal faces under study. The experimental results show that the modified PSR model is more accurate at generating load-independent hardness data and also for explaining the origin of ISE.

Vickers micro-hardness study of the effect of fluoride mouthwash on two types of CAD/CAM ceramic materials erosion

BackgroundThe aim of this study was to evaluate the protective effects of fluoride mouthwash on the surface micro-hardness of two types of CAD/CAM ceramics after exposure to acidic solutions.Methods40 samples (5 × 5 × 3 mm3) were prepared from two different ceramics: Vitabloc Mark II CAD, and IPS e.max CAD. The samples were randomly divided into 5 groups in each ceramic (n = 8) immersed in different solutions: Gs: saliva: GGA: gastric acid, GAA: acetic acid, GFGA: sodium fluoride + gastric acid, GFAA: sodium fluoride + acetic acid. The microhardness of samples was measured before and after immersion in different solutions by Vickers microhardness tester. By subtracting the microhardness values after and before immersion, the microhardness changes of the samples were obtained. Data were analyzed by Two-way analysis of variance, one-way analysis of variance, and Tukey test (α = 0.05).ResultsImmersion in different solutions reduced the microhardness. Microhardness loss was significantly affected in G FAA and G FGA groups in both types of ceramics (P < 0.05). For Vitabloc Mark II groups, the microhardness loss was significantly higher in GFAA and GFGA compared to IPS e.max CAD P < 0.001).ConclusionFluoride mouthwash in conjunction with acidic solutions may adversely affect microhardness of Vitabloc Mark II CAD, and IPS e.max CAD that may consequently compromise the clinical service. Vitabloc Mark II CAD was significantly more affected than IPS e.max CAD.

SURFACE MODIFICATION OF SS-316 TO ENHANCE CAVITATION RESISTANCE THROUGH COMPOSITE MICROWAVE CLADS

Microwave cladding is one of the latest surface engineering techniques, which has been used to improve the surface properties of a material. This technique overcomes almost all limitations of the existing methods. In this study, Ni-based+10% Cr3C2 composite clads have been developed in domestic microwave oven of 2.45-GHz frequency and 900-W power. The developed composite clads have been characterized using various standard mechanical and metallurgical techniques like SEM/EDS, XRD and Vickers microhardness tester. Cavitation erosion resistance of developed composite clads has also been examined at different parametric conditions. The microstructure analysis exhibits that the developed composite clads of 730-[Formula: see text]m thickness are free of cracks (solidification and interfacial) and less porous. The presence of various intermetallic and hard carbide phases like FeNi3, CrSi2, Cr3Ni2SiC, SiC and NiC is confirmed from the XRD analysis. The Vickers microhardness study reveals that the average microhardness of clad region is [Formula: see text] HV[Formula: see text]. The cavitation erosion study (at different parametric conditions using vibratory cavitation erosion testing) reveals that the developed composite clads perform much better under cavitation erosion environment than the SS-316 substrate. The stand-off distance is found to be the most dominating factor followed by amplitude and immersion depth.

Integrity in linear and nonlinear optical properties of L-tyrosine doped bis thiourea cadmium acetate single crystal

The slow evaporation technique was adopted for the growth of L-tyrosine doped Thiourea (Bis) Cadmium Acetate (CTA) single crystal. The doped crystals were characterized by powder X-ray diffraction, FT-IR analysis, SHG Studies, UV-vis and Vickers microhardness studies. The UV-visible absorption spectrum is found to have improved optical parameters than pure CTA. The optical study revealed that the doped CTA crystal has high transmission with low cut off wavelength of 290 nm. The optical band gap was found to be 4.14 eV. The Second harmonic generation efficiency measured using Nd-YAG laser is 3.64 times higher than pure CTA.

High-Temperature Dry Sliding Wear Behavior of Ti–10V–2Fe–3Al

AbstractIn this study, the microstructure, high-temperature tribological performance, and mechanical properties of solution-aged Ti–10V–2Fe–3Al were investigated. The microstructure of solution-aged Ti–10V–2Fe–3Al reveals a bimodal α and β microstructure with uniformly dispersed α precipitates in the β matrix phase. The hot tribological performance of solution-aged Ti–10V–2Fe–3Al was investigated at different temperatures (28, 250, 350, and 450 °C) in a high-temperature pin-on-disc configuration. The wear mechanisms were evaluated at the worn-out surface using a scanning electron microscope (SEM). The abrasive wear mechanism is predominant at 28 °C and 250 °C testing conditions, whereas the oxidation and delamination are dominant wear mechanisms at 350 °C and 450 °C testing conditions. The worn-out surface at different temperature conditions was characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectrometer (EDS) analysis. The absence of protective oxide formation at 28 °C and intermittent protective oxide formation at 250 °C testing condition are ineffective in protecting the surface from wear damages and high wear loss. The protective tribo-oxide formations at 350 °C and 450 °C are continuous and provide improved wear resistance behavior of the material. The V2O5-rich tribo-oxide layer formation at 350 °C offers excellent wear resistance and protection against wear damages among the testing conditions. The Vickers microhardness study of the samples tested at different temperature conditions shows significant differences in the hardness magnitude at the cross section.

Trypan blue stained KAP crystal: A comparative study on morphological, structural, optical, di-/piezo-electric and mechanical properties

Single crystals of pure and trypan blue (TB; C34H28N6O14S4) stained (0.01 mol%) potassium hydrogen phthalate (KAP; C8H5KO4) were grown by slow evaporation solution method. Experimentally obtained crystal habit of KAP matched well with the theoretical morphology predicted using BFDH laws. Eight planes ({111} & {111¯}) out of total fourteen planes got selectively coloured by TB dye molecules. Affinity of TB dye towards specific growth sectors can help various scientists to understand the selective nature of dye molecules and thereby will help in proposing novel tailor-made stained photonic crystals. UV–Vis-NIR spectra for TB stained KAP crystals displayed a strong absorption peak at 563 nm, which was blue shifted for TB dye in KAP matrix relative to neutral aqueous solution of TB dye. This shift in the absorption maxima towards lower wavelength confirms the successful colour insertion into selective growth sectors of stained KAP crystals. The effect of TB staining on various optical parameters namely optical conductivity, optical band gap, refractive index and extinction coefficient of host KAP matrix was studied. The structural conformation and the recognition of different functional groups present in as grown KAP crystals were approved by powder XRD and FTIR studies, respectively. Dielectric constant increased and dielectric loss decreased as a result of TB dye staining in KAP material. The piezoelectric conversion efficiency got increased from 1.22 pC/N for un-dyed KAP single crystal to 1.53 pC/N for TB stained KAP single crystals. In Vickers micro-hardness studies, TB stained KAP crystals displayed better mechanical strength.

Synthesis and crystal growth of 2, 3-dimethyl-N-[2-(hydroxy) benzylidene] aniline: An organic second-order non-linear optical crystal for non-linear optical (NLO) applications

Abstract Optically transparent organic single crystal of 2,3-Dimethyl-N-[2-(hydroxy) benzylidene] aniline (DHBA) has been successfully prepared, and the single crystals were grown with dimensions up to 10 × 5 × 2 mm3 by using slow evaporation solution growth method in methanol. Single crystal X-ray diffraction (SCXRD) study revealed that the DHBA was crystallized in an orthorhombic crystal structure with P212121 space group, which is a crucial parameter for the second harmonic generation. The existence of various functional groups in the DHBA molecular structure was characterized by FT-IR, FT-Raman, and 1H NMR techniques. UV–Vis–NIR absorption study reveals that the lower cut-off wavelength at 464 nm with transparency over the Vis-NIR spectral regions. The photoluminescence (PL) spectra of DHBA crystal exhibit a green emission centered at 538 nm. The thermal stability and melting temperature of DHBA was assessed by TG/DTA analysis. Vickers microhardness studies have also been investigated to check the mechanical stability of the grown crystal. The dielectric properties of DHBA have been tested in various frequency ranges from 50Hz to 5 MHz at three different temperatures (308K, 323K, and 348K), and the results are discussed. The second order NLO efficiency of the powdered DHBA crystal is three times greater than that of KDP. All of these results imply that DHBA crystal could be a desirable candidate for non-linear optical applications.

Growth, Experimental Studies and DFT Calculations on Gallic acid 5-Nitrouracilate Single Crystals for Non-linear Optical Applications

The growth and characterization of gallic acid 5-nitrouracilate (GA5NU) single crystals were grown using slow evaporation solution growth technique at room temperature. Single crystal XRD analysis revealed that the grown crystal belongs to monoclinic crystal system. HOMO-LUMO and molecular electrostatic potential (MEP) has been visualized and analyzed. The presence of various functional groups present in the host material was examined using FTIR spectra. Mechanical stability of the grown crystal is validated using Vickers microhardness study and the grown crystal belongs to soft material category. Various hardness parameters like fracture toughness, brittleness index, elastic stiffness constant, tensile strength and other hardness parameters were also calculated. Thermal stability of the grown crystal was also determined. The second harmonic generation (SHG) efficacy of grown crystal was 2.97 times higher than potassium dihydrogen phosphate (KDP), which makes the grown crystal as suitable candidate material for non-linear optical applications.

Crystal structure, Hirshfeld surface, DFT calculations of guanidinium 4-hydroxybenzoate monohydrate (GuB) single crystal: A potential candidate for nonlinear optical applications

The crystal description of GuB crystal was studied using x-ray diffraction study. The bonding interactions of GuB single crystal were discussed. The presence of functional groups of GuB crystal was determined using FT-IR spectral study. The defects present on the surface of GuB crystal was examined through chemical etching study. The mechanical stability of GuB crystal was analyzed using Vicker's microhardness study. The variation of dielectric constant and dielectric loss of GuB single crystal was recorded for different temperatures. Hirshfeld surface analysis was done for the GuB molecule to analyze the molecule interaction behavior. The theoretical investigation of GuB molecule was carried out using DFT calculation. The GuB molecule was optimized using B3LYP/6–31+g(d,p) basis set. The bond angle and bond length obtained theoretically was compared with the experimental values. The Frontier Molecular Orbital analysis ascertained the bandgap energy of GuB molecule. The nonlinear behavior and dipole moment of GuB molecule was analyzed using hyperpolarizability calculations.

Growth, mechanical, thermal and nonlinear optical properties of magnesium doped ninhydrin crystals

Abstract The slow evaporation procedures were executed to develop pure (PN) and magnesium doped ninhydrin (M4N) single crystals. Various required characterizations were focused to find structural, mechanical, thermal and nonlinear optical properties. From the XRD studies, the crystal structure of PN and M4N single crystal is monoclinic and space group is P21. Mechanical power of PN and M4N single crystal was observed using Vickers microhardness studies. The coefficients of work-hardening values are calculated as 6.45 and 5.06 for undoped and doped ninhydrin M4N crystals. With the use of thermal analysis, the decomposition temperatures of the crystals were studied. The Second Harmonic Generation (SHG) efficiency of PN and M4N were tested by using the powder Kurtz technique and it illustrates that the addition of magnesium leads to improve the NLO behaviour of the M4N crystals.

Structural, third-order nonlinear optical properties and optical limiting studies of novel zinc potassium aluminum sulfate nonadecahydrate single crystal

The crystal of zinc potassium aluminum sulphate nonadecahydrate (ZPASDH) was first time grown by the slow evaporation method. Powder X-ray diffraction (PXRD) study was used to evaluate the structure of ZPASDH crystal. Using Fourier transform infra-red (FTIR) analysis the functional groups were identified. The UV–Vis spectrum recorded for the grown ZPASDH crystal, from the spectrum optical cutoff wavelength is observed at 387 nm and the optical band gap was also determined. Thermo gravimetric analysis (TGA) was used for confirmation of thermal stability of grown crystal. Mechanical strength of the ZPASDH single crystal was confirmed by Vickers microhardness study. Third-order nonlinear refractive index (n2 = 1.11 × 10−9 cm2/W), nonlinear absorption coefficient (β = 5.31 × 10−5 cm/W) and optical limiting behavior of ZPASDH crystal have been determined by Z-scan technique.

Microstructural studies on aluminium metal matrix composite (Al7075-SiC) fabricated through stir casting process

In the present work Al7075 metal matrix reinforced with silicon carbide (SiC) powder is fabricated through stir casting route. Metal matrix composites were manufactured by altering percent weight fraction of silicon carbide powder as 5% & 7.5% by weight with average particle size of 50 µm. Microstructural evaluation and Vickers microhardness studies on stir casted Aluminium 7075 alloy which has silicon carbide (SiC) reinforcement are reported in current paper. After stir casting of composites, manufactured composite samples are examined by using optical microscope and scanning electron microscope (SEM) in order to study distribution SiC particles in aluminium matrix. The microstructural observations on metal matrix composites have reported the presence of SiC reinforcement in the matrix which are very much fairly distributed into the matrix phase. Also it can be seen that there is little clustering of SiC particles in Al7075 matrix and porosity in manufactured composites. It is also been found that microhardness of aluminium metal matrix composites was improved with increment in reinforcement content.

Studies on cryogenically treated WC-Co insert at different soaking conditions

ABSTRACTTool wear and tool replacement significantly increases the machining time and subsequently increase the production cost. To enhance tool life, various surface modification techniques are adopted such as nitriding, hard coating, heat treatments, cyaniding, etc. In the present study, the tungsten carbide-cobalt (WC-Co) cutting tool is treated cryogenically at −196°C with the different soaking periods of 24, 48 and 72 h. The performance characteristics of the treated cutting tool are measured on Al6063 under turning operation at various machining conditions and the results are compared with untreated tools. An experimental design with Cutting velocity, depth of cut and feed rate as machining parameters have been evaluated, with roughness and tool wear rate as the output variables of the study. Minimum tool wear and acceptable level of surface finish are observed on cryogenically treated inserts and Al6063, respectively. An increase in the soaking period in a deep cryogenic environment leads to having excess tool wear and subsequently affects the surface finish. Twenty-four hours and 48 h deeply cryo-treated insert exhibits fine microstructural observation which reveals the formation and distribution of η carbide particles, in turn, results in improved hardness and wear resistance. The conformity of the above results is ensured through Vickers micro-hardness and surface morphological studies.

Effect of L-asparagine as dopant on the growth and characteristics of ammonium tetroxalate dihydrate single crystal

Abstract Single crystals of L-asparagine doped ammonium tetroxalate dihydrate were grown using slow evaporation solution growth technique with deionized water as a solvent. The shift and intensity of the peaks in the single crystal X-ray diffraction and Fourier transform infrared analyses confirmed the inclusion of L-asparagine in the ammonium tetroxalate dihydrate crystal structure. The optical transmission characteristics viz. optical band gap, optical conductivity, etc., were determined. Thermal studies revealed the occurrence of anomalies at 135.3 °C and 221.7 °C leading to the possibility of phase transitions and thereby, ferroelectric behavior. Vickers microhardness studies enabled determination of various microhardness parameters. Dielectric behavior was analyzed by varying the temperature and frequency. Anomalies were observed at 135 °C and 221 °C suggesting the existence of ferroelectric nature of the compound. Self-defocusing effect was observed. The polarization-electric field hysteresis loops showed a pinched effect due to defects induced by inclusion of dopant. The crystals were characterized by single crystal XRD, FT-IR, DRS, UV-Vis-NIR, Vickers microhardness test as well as thermal and dielectric techniques. In brief, L-asparagine as a dopant in ammonium tetroxalate dihydrate altered various physical properties of the crystals. They were highly transparent in the visible region with a wider optical band gap, softer material than the parent, higher phase transition temperature of 135 °C, negative nonlinearity and self-defocusing ability.

Microhardness study of Cd1-x ZnxTe1-ySey crystals for X-ray and gamma ray detectors

We performed a detailed Vickers microhardness study of quaternary material Cd1−x ZnxTe1−y Sey (CZTS), which is currently under investigation for applications in the detection of hard X-rays and gamma rays. In this frame, the Vickers microhardness method, resistivity mapping, low-temperature (4.2 K) photoluminescence, and Se energy dispersive X-ray spectroscopy (EDX) composition analysis were employed along the crystal growth axis. The microhardness values measured at 50 g load (HV 0.05), bandgap, and crystal composition along the crystal axis have been correlated. We also performed a comparative study of a set of CdTe, CdZnTe, and CdTeSe samples. We observed a significantly higher microhardness in CZTS crystals when compared to CdZnTe crystals. While in the CdZnTe crystals the microhardness increases by approx. 2.1 HV 0.05 per 1% of Zn + Se content, in CZTS crystals this value is 4.1 HV 0.05. This result indicates a possible additional strengthening of the effect when Zn and Se are mixed in the CdTe lattice.

Exploring remarkable impact of thiourea in enhancing the performance of NH4H2PO4 single crystal for photonic device applications

The present investigation is primarily aimed to investigate the impact of thiourea on characteristic properties of ammonium dihydrogen phosphate (NH4H2PO4, ADP) crystal to emphasize its utmost liability for designing nonlinear optical device applications. The most commercial slow solvent evaporation method has been opted to grow the undoped and thiourea doped ADP single crystals. The single crystal X-ray diffraction study has been employed to determine the structural parameters of undoped and thiourea doped ADP crystal. The elemental analysis has been performed to confirm the presence of thiourea in ADP crystal. The UV–visible studies have been carried out within 200–1100 nm to examine the constructive impact of thiourea on optical transparency and vital linear optical parameters (extinction coefficient, refractive index and reflectance) of ADP crystal. The Kurtz-Perry test has been employed to ascertain the enhancement in SHG efficiency of ADP crystal due to presence of thiourea. The third order nonlinear optical nature and properties such as nonlinear absorption (β), refraction (n2) and susceptibility (χ3) of T-ADP crystal has been examined at 632.8 nm by imposing the Z-scan studies. The color centered photoluminescence emission behavior of pure and thiourea doped ADP crystal has been investigated within 320–650 nm. Vickers microhardness study has been imposed to evaluate the role of thiourea in uplifting the hardness parameters of ADP crystal. The dielectric parameters (dielectric constant and dielectric loss) of undoped and thiourea doped ADP crystal has been comparatively investigated within the temperature range of 25–100 °C. The surface growth habitat of thiourea doped ADP crystal has been investigated by means of chemical etching technique.

Single crystal growth of l-tartaric acid and its characterization for optical applications

An optical material is a fundamental in the field of information along with measurement of laser applications. Crystals of organic compounds are very well known for its highly efficient behavior towards the optical activities. In the present study, slow evaporation solution growth technique has been adopted for the growth of l-tartaric acid (LTA). The phase and structural information was assessed with powder X-ray diffraction and grown single crystal’s quality was tested through high resolution X-ray diffraction and found to be reasonably good. The composition bonding between the molecules was revealed out by Fourier-Transform Infrared Spectroscopy method. The Ultraviolet–Visible spectroscopy exposes the excellent transmittance properties of LTA crystal. Photoluminescence spectrum shows strong emission in the violet region. Optical properties are measured to know its behavior towards electromagnetic spectrum which is further analyzed by ultrafast pump probe spectrometry and the determination of non-linear optical absorption coefficient was also taken into account with respect to the absorbance spectra. Moreover, Vickers microhardness studies were carried out to check its mechanical behavior.

Growth and Characterization of Adipic Acid Doped Potassium Hydrogen Phthalate: A Nonlinear Optical Single Crystal

Adipic acid doped potassium hydrogen phthalate (AAKHP) and pure potassium hydrogen phthalate single crystals were grown by slow evaporation method. Single crystal X-ray diffraction analysis was carried out to determine the lattice parameters in a = 6.47 Å, b = 9.59 Å, c = 13.25 Å and space group of Pca21. This confirms the grown AAKHP belongs to the orthorhombic system. Various diffracting planes of the grown crystal were indexed using powder X-ray diffraction study. Fourier-transform infrared studies confirm the presence of various functional groups in the grown crystal. The transmittance spectrum shows that the lower cutoff wavelength is around 290 nm. The nonlinear optical property of the grown crystal has been studied by Kurtz powder second harmonic generation (SHG) analysis. EDAX analysis confirms the presence of various elements in the AAKHP crystal. Vickers micro-hardness studies are used for the analysis of mechanical behaviour of the grown crystal. The paramagnetic nature of the grown crystal was confirmed by vibration spectrum magnetometer technique.