Phase Quantification Research Articles

Surface Chemistry Studies of Emission and Thermal Behaviour of Developed Composites for Building Ceiling Materials

The emission of harmful elements from burning building ceiling materials and their attendant health effects on inhabitants within the vicinity of the emitted harmful elements is increasingly becoming a source of concern globally. Hence, the need to develop eco-friendly flame-retardant composite materials suitable for house ceiling purposes to forestall unwanted toxic emissions. This work identified the chemical structure of developed composite products and their emission performance during combustion. X-ray Diffraction (XRD) analysis was used for phase quantification and E550 combustion gas analyzer for emission characterization of the developed composites. Thermolyne 950 °C oven was employed for the combustion analysis of the prepared composite at 500 °C. Quasi negligible SO2 and CO2 levels existed, while A4, 0.3Aldr0.23Cmt0.3Si0.05G0.12CS recorded maximum CO level, indicating toxic affluence. The low mass losses of all composite materials, especially for A2, 0.6Aldr0.34Cmt0.05G0.01OBSretard significantly due to its activities by the retardant constituent. The flame retardant nature of all produced composites was evidenced in their elemental composition. There was an absence of a flammable element and stable insulating compounds providing retardance to flame occurrences. These suppressions in flame inclination of the reinforced materials were noticed within the boundaries of the ceiling crystals from the structural examination. The intermetallic phase from the diffraction intensities showed the presence of a significant second bond interstitial solid-phase across the matrix, especially for 0.6Aldr0.34Cmt0.05G0.01OBS ceiling material. This study has established the eco-friendliness of developed building ceiling composite and the potential to reduce the importation of building ceilings. The developed ceiling composite evidently demonstrated high potential to compete favourably with imported ceiling materials in terms of fire resistance performance, low cost of production, and abundant availability of raw materials in the environment. Oil beanstalk is a novel material introduced as a reinforcement to developed building ceiling composite. This research provides a blueprint for manufacturers, construction and allied industry, and stakeholders in developing eco-friendly flame retardant composite ceilings whose materials can be readily sourced locally available in the environment.

Enabling phase quantification of anhydrous cements via Raman imaging

The phase composition of Portland cements is typically determined using conventional techniques like X-ray Diffraction (XRD) Rietveld analysis, optical microscopy point counting, and electron microscopy. However, these techniques have several limitations that may affect their accuracy in certain sample-specific scenarios. Here, we report a highly accurate phase quantification of 11 different types of commercial, anhydrous cements using a new and complementary technique: Raman imaging. Specifically, for the 4 principal phases, composition from our extensive data (250,000 Raman spectra per sample, error < 0.71%) and those obtained from XRD Rietveld and supplier data have high coefficients of determination (R2 > 0.98, mean deviation <2%). Additionally, we also quantify 8 secondary phases present in cement clinkers (gypsum, anhydrite, bassanite, syngenite, dolomite, calcite, quartz, and portlandite) with a high degree of confidence, thereby demonstrating that Raman imaging is a highly versatile tool for anhydrous phase quantification in a broad variety of cements.

Mounted Single Particle Characterization for 3D Mineralogical Analysis—MSPaCMAn

This paper demonstrates a new method to classify mineral phases in 3D images of particulate materials obtained by X-ray computed micro-tomography (CT), here named mounted single particle characterization for 3D mineralogical analysis (MSPaCMAn). The method allows minimizing the impact of imaging artefacts that make the classification of voxels inaccurate and thus hinder the use of CT to characterize natural particulate materials. MSPaCMAn consists of (1) sample preparation as particle dispersions; (2) image processing optimized towards the labelling of individual particles in the sample; (3) phase identification performed at the particle level using an interpretation of the grey-values of all voxels in a particle rather than of all voxels in the sample. Additionally, the particle’s geometry and microstructure can be used as classification criteria besides the grey-values. The result is an improved accuracy of phase classification, a higher number of detected phases, a smaller grain size that can be detected, and individual particle statistics can be measured instead of just bulk statistics. Consequently, the method broadens the applicability of 3D imaging techniques for particle analysis at low particle size to voxel size ratio, which is typically limited due to unreliable phase classification and quantification. MSPaCMAn could be the foundation of 3D semi-automated mineralogy similar to the commonly used 2D image-based semi-automated mineralogy methods.

Evaluation of the Effect of Minor Additions in the Crystallization Path of [(Fe0.5Co0.5)0.75B0.2Si0.05]100-xMx Metallic Glasses by Means of Mössbauer Spectroscopy

Understanding the crystallization of metallic glasses is fundamental in the design of new alloys with enhanced properties and better glass-formability. The crystallization of a series of Fe-based metallic glasses of composition [(Fe0.5Co0.5)0.75B0.2Si0.05]100-xMx (M = Mo, Nb and Zr) has been studied by means of differential scanning calorimetry and transmission Mössbauer spectroscopy. This latter technique allows the following of the microstructural evolution of the studied alloys through the identification and quantification of the several Fe-containing crystalline phases and also through the changes in the amorphous structure at the initial stages of crystallization. The results show that the crystallization products are the same for all the studied compositions (α-Fe, Fe2B, (FeCo)23B6 and a paramagnetic remnant) although with different relative proportions and the crystallization of a phase without Fe in the alloys with Zr. Moreover, the addition of Zr favors the crystallization of α-Fe causing a detrimental effect on the glass forming ability, while the increase in Mo content up to 6 at% favors the crystallization of (FeCo)23B6. The different amount of α-Fe and borides is presented as a measure of the glass forming ability of this type of alloys.

Phase Quantification of Regular and Turbo-stratified Graphite in Cast Iron by X-ray Diffractometry/Rietveld Refinement

Phase Quantification of Regular and Turbo-stratified Graphite in Cast Iron by X-ray Diffractometry/Rietveld Refinement

Study of the Influence of Sintering Atmosphere and Mechanical Activation on the Synthesis of Bulk Ti2AlN MAX Phase Obtained by Spark Plasma Sintering.

The influence of the mechanical activation process and sintering atmosphere on the microstructure and mechanical properties of bulk Ti2AlN has been investigated. The mixture of Ti and AlN powders was prepared in a 1:2 molar ratio, and a part of this powder mixture was subjected to a mechanical activation process under an argon atmosphere for 10 h using agate jars and balls as milling media. Then, the sintering and production of the Ti2AlN MAX phase were carried out by Spark Plasma Sintering under 30 MPa with vacuum or nitrogen atmospheres and at 1200 °C for 10 min. The crystal structure and microstructure of consolidated samples were characterized by X-ray Diffraction, Scanning Electron Microscopy, and Energy Dispersive X-ray Spectroscopy. The X-ray diffraction patterns were fitted using the Rietveld refinement for phase quantification and determined their most critical microstructural parameters. It was determined that by using nitrogen as a sintering atmosphere, Ti4AlN3 MAX phase and TiN were increased at the expense of the Ti2AlN. In the samples prepared from the activated powders, secondary phases like Ti5Si3 and Al2O3 were formed. However, the higher densification level presented in the sample produced by using both nitrogen atmosphere and MAP powder mixture is remarkable. Moreover, the high-purity Ti2AlN zone of the MAX-1200 presented a hardness of 4.3 GPa, and the rest of the samples exhibited slightly smaller hardness values (4.1, 4.0, and 4.2 GPa, respectively) which are matched with the higher porosity observed on the SEM images.

Relationships between fracture toughness, Y2O3 fraction and phases content in modern dental Yttria-doped zirconias

The relationship between fracture toughness and Yttria content in modern zirconia ceramics was revised. For that purpose, we evaluated here 10 modern Y2O3-stabilized zirconia (YSZ) materials currently used in biomedical applications, namely prosthetic and implant dentistry. The most relevant range between 2-5 mol% Y2O3 was addressed by selecting from conventional opaque 3 mol% YSZ up to more translucent compositions (4−5 mol% YSZs). A technical 2YSZ was used to extend the range of our evaluation. The bulk mol% Y2O3 concentration was measured by X-Ray Fluorescence Spectroscopy. Phase quantification by Rietveld refinement considered two tetragonal phases or an additional cubic phase. A first-account of the fracture toughness (KIc) of the pre-sintered blocks is given, which amounted to 0.4 – 0.7 MPa√m. In the fully-densified state, an inverse power-law behavior was obtained between KIc and bulk mol% Y2O3 content, whether using only our measurements or including literature data, challenging some established relationships. A linear relationship between KIc and the fraction of the transformable t-phase was established within the range of 30–70 vol%.

Identification of Degradation Parameters in SOC Using In-Situ and Ex-Situ Approaches

Solid oxide cells (SOC) have been comprehensively tested under fuel cell (FC) and electrolysis (EC) modes over the past decades. Recent SOC activities focus on upscaling the applications to MW scales with target operation for several 10,000 hours. These long lifetimes require new approaches for durability testing. In the present study, the influence of different operating parameters on degradation were studied by long-term cell testing (in situ treatment). Based on the results, accelerating parameters for ex situ treatment were identified, which is a cheaper and time saving approach as compared to conventional cell/stack long-term testing. Two commercial SOC cell designs were studied: Anode supported cells (ASC) and Electrolyte supported cells (ESC). These cells are composed of LSCF cathodes with a CGO barrier layer, YSZ electrolyte and Ni based fuel electrodes. In case of ASCs, the fuel electrode consists of Ni-YSZ cermet and of Ni-CGO in case of ESCs. A comparison to field operated stacks was performed to understand the different degradation mechanisms observed under real, long operation.Single cells were characterized in detail and then operated over 1000 h either in FC or EC mode, and with different steam contents in hydrogen to the fuel electrode. After these conventional tests (in situ), the fuel electrode of fresh cells were exposed to similar temperature and gas compositions for 1000 h but without application of current loads (ex situ), thus studying the effect of temperature and steam on durability of the fuel electrode. After the in-situ and ex-situ treatments, the cells were characterized in detail through deconvolution of EIS spectra using distributions of relaxation times (DRT) and complex least squares approach (CNLS) fitting using appropriate equivalent circuit models (ECM). In addition, the microstructure of the cells were studied after the in-situ and ex-situ operation and compared to the reference cells. For this purpose, secondary electron imaging was done at low accelerating voltage (1keV) using Zeiss Ultra field emission microscope and a quantification of the different phases was performed. The results give insight into the effect of the different operating parameters for the different cell configurations. The two cell types respond differently in terms of degradation under long term tests with highly humidified hydrogen fuel under in situ (under current load) vs. ex situ conditions. In FC mode, the ESCs seem to degrade less in ex situ tests with high steam partial pressures to the fuel electrode as compared to the in situ tests operated under similar steam conditions, particularly regarding the polarization resistance. The different aggravated operation parameters (temperature, steam composition, current density) have differing impact on the cell microstructure as well. For instance, in ESCs, during ex situ treatment with high steam content to the fuel electrode and high temperatures (900º C), there is severe agglomeration of the CGO particles in the fuel electrode. Furthermore, agglomerates of Ni particles are engulfed by the CGO within the functional layer (~3-15 microns from the electrolyte). A similar coverage of the Ni particles by the CGO is observed also at 850 ºC although the Ni particles are finer in size. A similar effect was also observed for the Ni particles after in situ tests. Figure 1

Phase transition detection in liquid crystal analysis by mathematical morphology

Light polarizing-microscopy is a technique applied to identify different phases in liquid crystal analysis. With the linear increase of the temperature of the liquid crystal sample, in the image sequence acquisition stage, changes in the images, generated by the microscope, are observed. Such changes are related to the different phases and phase transitions. Based on Mathematical Morphology, this work aims to propose a new method for detection and quantification of phase and phase transitions. For this purpose lyotropic liquid crystal samples, exhibiting the classic sequence of phases: reentrant isotropic (Ir)→ discotic nematic (ND)→ biaxial nematic (NB)→ calamitic nematic (NC)→ isotropic (I) are studied. The connected morphological operators were shown to be very efficient to extract information from the complex structures. Once the image sequence is acquired, it may be processed by techniques designed to phase transition detection. From the image analysis point of view, texture changes are more evident when observed the all image sequence, and it allows to extract many features that may be applied to detect phase transitions and to characterize each phase as well. In this proposal, such features are extracted from the residue of a graylevel area opening operator.

Oxyhemoglobin Concentration and Oxygen Uptake Signal During Recovery From Exhaustive Exercise in Healthy Subjects-Relationship With Aerobic Capacity.

This proof of concept study is dedicated to the quantification of the short-term recovery phase of the muscle oxygenation and whole-body oxygen uptake kinetics following an exhaustive cycling protocol. Data of 15 healthy young participants (age 26.1 ± 2.8 years, peak oxygen uptake 54.1 ± 5.1 mL∗min-1∗kg-1) were recorded during 5 min cool down-cycling with a power output of 50 W on an electro-magnetically braked cycle ergometer. The oxygen uptake (VO2) signal during recovery was modeled by exponential function. Using the model parameters, the time (T1/2) needed to return VO2 to 50% of VO2peak was determined. The Hill’s model was used to analyze the kinetics of oxyhemoglobin concentration (Sm, %), non-invasively recorded by near-infrared spectroscopy (NIRS) over the M. vastus lateralis. Analysis of the Pearson correlation results in statistically significant negative relationships between T1/2 and relative VO2peak (r = −0.7). Relevant significant correlations were determined between constant defining the slope of VO2 decrease (parameter B) and the duration of the anaerobic phase (r = −0.59), as well as between Hill’s coefficient and average median Smmax for the final 2 min of recovery. The high correlation between traditional variables commonly used to represent the cardio-metabolic capacity and the parameters of fits from exponential and Hill models attests the validity of our approach. Thus, proposed descriptors, derived from non-invasive NIRS monitoring during recovery, seem to reflect aerobic capacity. However, the practical usefulness of such modeling for clinical or other vulnerable populations has to be explored in studies using alternative testing protocols.

Cueing Changes in Peak Vertical Ground Reaction Force to Improve Coordination Dynamics in Walking

s Biofeedback has been effectively implemented to improve the mediation and distribution of joint loads during gait, however, the inability to effectively coordinate lower limb movement by altering loading patterns may increase pathological stress and risk of injury and deleterious joint changes. This study examined the influence cueing an increase or decrease in lower extremity loading has on inter- and intralimb joint coordination during gait, applied herein for 12 persons following anterior cruciate ligament reconstruction across three loading conditions (control, high, and low). Visual biofeedback was presented on a screen via a force-measuring treadmill with targeted changes prescribed based on stride-to-stride peak vertical ground reaction forces bilaterally. The pattern and stability of coordination dynamics among each of the ankle, hip and knee joint pairs were assessed via discrete relative phase and cross-recurrence quantification analyses for each condition. High and low loading altered the pattern and stability of intralimb coordination; low loading led to decreased coordination stability (20° greater than control condition) and high loading resulted in a more tightly coupled coordination pattern (higher %CDET). With thoughtful consideration for movement control, biofeedback can be used to target mechanisms leading to long-term deleterious joint adaptations.

Introdução à quantificação de fases cristalinas: Um exemplo prático e ilustrativo sobre os fundamentos.

X-ray powder diffraction is a powerful technique used in the characterization of materials, since it has the ability to undoubtedly differentiate several crystalline phases, even if they have the same composition. In addition to identification, a quantification of the phases present in a sample provided is also possible. Normally the phase quantification is done using computer programs that, increasingly, have a friendly graphical interface and an easy access refinement routine, where the user does not need to have much understanding of the concepts physics and mathematics of the technique to reach a result reasonable. In this context, it is proposed in this work to discuss some basic concepts of phase quantification, exposing a practical example for determining the mass percentage of using a standard mixture model of 75% Magnetite and 25% Hematite.

Siderite-calcite (FeCO3–CaCO3) series cement formation by accelerated carbonation of CO2(g)–H2O–Fe–Ca(OH)2 systems

Carbonation-cementation and bulk reaction mechanisms are studied in systems containing closely packed mixes of particulate Fe (0) (~10 μm) and Ca(OH)2 (0%, 5%, 10% and 15% w/w of Ca(OH)2) subjected to elevated CO2-pressure (1, 5, 10, and 20 barg) and temperature (30 °C and 60 °C). Solid solutions of (CaxFe1-x)CO3 series minerals are observed through shifting and broadening of XRD-reflections with variations in Ca(OH)2 content, CO2-pressure and temperature. The product morphologies varied from rhombohedral in non-Ca(OH)2 systems, to distorted rhombohedral (at 60 °C) and scalenohedral (at 30 °C) in the systems containing Ca(OH)2. An X-ray diffraction-based interpolation method is developed to discern mixed and end-member carbonates for more accurate bulk phase quantification. Based on these observations, variations in cementation performances are explained. Exceptional formation of an Fe-LDH and a (Ca,Fe)-LDH has also been observed in some systems. Interestingly, these LDH phases were stable even after being exposed to ambient conditions for more than 75 days.

Production of low-CO2 cements using abundant bauxite overburden “Belterra Clay”

Eco-friendly binders are among the opportunities to reduce the approximately 8% global CO2 emissions generated by the cement industry, with calcium-sulphoaluminate (CSA) -based cements standing as a potential low-CO2 alternative to the world most used ordinary Portland cements (OPC). Belterra Clay (BTC), an abundant low-cost alumina-rich clay overburden on the huge bauxite reserves of the Brazilian Amazon was tested to produce CSA-based binders. Successive Designs of Experiments were used to prepare mixtures containing BTC, CaCO3, and gypsum, seeking the maximum BTC and minimal CaCO3 consumption under the lowest possible temperature to maximize CSA's main phase ye'elimite, Ca4Al6(SO4)O12, in the clinkers. X-ray powder diffraction accompanied by Rietveld phase quantifications, X-ray fluorescence, and scanning electron microscopy were used to characterize the obtained products and guide the experimental work. CSA-belite and CSA-ternesite clinkers were successfully sintered at 1250 °C using up to 42% of BTC. The hydration of selected clinkers was investigated by isoperibolic heat flow calorimetry after blending with gypsum at 95:5 and 90:10 mass ratios. The main hydrations of the clinkers were faster (within 24 h) when using 5% of gypsum. Ettringite was the main hydrated phase, followed by kuzelite, straetlingite, and hemicarboaluminate. Produced mortars reached up to 40 Mpa after 28 days of curing, a strength development comparable to that of an OPC (46 Mpa) tested under the same conditions. BTC, currently a drawback during bauxite mining and rehabilitation of mined areas, was successfully used to produce clinkers that generate ca. 30% less CO2 during calcination when compared to OPC, with further CO2 and energy savings expected because of the required lower sintering temperature.

Bimanual Coordination in a Whole-Body Dynamic Balance Sport, Slacklining: A Comparison of Novice and Expert.

As previous studies have suggested that bimanual coordination is important for slacklining, the authors questioned whether this important skill plays a role in the performance of a fundamental task of slacklining. To address this question, the authors compared single-leg standing on the slackline between novices and experts in terms of bimanual coordination dynamics within a dynamical systems framework using relative phase and recurrence quantification analysis measures. Five novices and five experts participated in the experiment. Participants were required to perform single-leg standing on a slackline. To collect motion data while slacklining, the authors used a 3D motion capture system and obtained time series data on the wrist position of both hands. The authors compared bimanual coordination dynamics between novices and experts. Although this preliminary study was limited in its sample size, the results suggest that experts tend to show a more antiphase coordination pattern than novices do and that they can more sustainably coordinate their hands compared with novices in terms of temporal structure in diagonal-related recurrence measures (i.e.,maxline, mean line, and percentage determinism).

Volatilized and Condensed Sb- and As-Bearing Phases Produced During Roasting of Cu-Rich Complex Concentrate in Nitrogen Atmosphere with Oxygen in Traces

A Cu-rich complex sulpfide concentrate (containing Sb as sulphosalts and gudmundite, and As as arsenopyrite) is roasted in Nitrogen atmosphere carrying traces of oxygen ({text{p}}^{{text{O}}_{2}} approx {10}^{-5.3}text{ bar)}. In situ measurements through QMS indicated that the volatilized species are mainly elemental sulfur, S2(g), and gaseous sulfur oxides. Sb- and As-bearing volatilized species could not be detected, owing to their low concentrations in the gas phase. Characterization studies through XRD and SEM-EDS confirmed that the condensates collected at room temperature during the roasting experiments comprised of (1) cyclo-octa sulfur, S8(s) and polysulfur oxides, Sn−xOx(s); (2) amorphous trisulfides of Sb and As; (3) and cubic crystalline trioxides of Sb and As. The solid phases in the condensate were found to be fine-sized (sub-micronic) and widely intermixed. Consequently, quantification of the solid phases in the condensates through direct measurement techniques like QEMSCAN was not possible. A novel approach of partial quantification of solid phases in the condensate through a stochastic model-based calculation approach is also presented. The model results suggested the occurrence of vapor-phase complexation of sulfides of Sb and As in the gas phase. Additional attributes of the volatilized species could be determined through a thermodynamic equilibrium calculation showing that the formation of the complex oxides, As4−nSbnO6(g), would be negligible compared to that of the complex sulfides, As4−nSbnS6(g).

Intraoral low-temperature degradation of monolithic zirconia dental prostheses: Results of a prospective clinical study with ex vivo monitoring

ObjectiveTo investigate the intraoral development and kinetics of low-temperature degradation (LTD) in second-generation 3 mol.% yttria-doped tetragonal zirconia polycrystal (3Y-TZP) monolithic prostheses, as well as the influence of masticatory mechanical stress and glaze layer on it. MethodsA total of 101 posterior tooth elements were included in a prospective clinical study, which included ex vivo LTD monitoring (at baseline, 6 months, 1 year, and 2 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and SEM. Four types of areas (1–2 mm2 surface, 6 on molars, and 4 on premolars) were analyzed on each element surface: occlusal, axial, glazed, or unglazed. Raman depth mapping and high-resolution SEM were performed on the selected samples. ResultsLTD developed in 3Y-TZP monolithic restorations 6 months after intraoral placement and progressed with time. After two years, the tetragonal-to-monoclinic transformation was non-uniform, with the presence of localized clusters of transformed grains. In axial areas, the grain aspect was typical of the classical nucleation-growth process reported for LTD, which progresses from the surface to a depth of several tens of microns. However, in occlusal areas, tribological stress generated surface crushing and grain pull-out from the clusters, which induced an underestimation of the aging process when the evaluation was limited to monoclinic phase quantification. Glazing cannot be considered a protection against LTD. SignificanceIf LTD occurs in dental prostheses in the same way as in orthopedic prostheses, its clinical impact is unknown and needs to be further studied.

Automated morphometrical characterization of material phases of fired clay bricks based on Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and Powder X-ray Diffraction

In this work, the microstructure of fired clay bricks made of five different Central European raw materials were investigated combining Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and Powder X-ray Diffraction. Based on these extensive experimental data, a largely automated process for characterization and morphometrical quantification of material phases building up the brick’s microstructures could be developed, showing a large microstructural variety of brick materials used in Europe. The comprehensive set of data collected allows for a deep understanding of these materials and provides a reliable basis for the development and optimization of fired clay bricks using micromechanical models.

Complex evolution of phase during the thermal investigation of Brushite-type calcium phosphate CaHPO4•2H2O

This study focused on a detailed examination of the thermal behavior of Brushite-based calcium phosphate (CaHPO4•2H2O, DCPD) to identify and characterize the intermediate phases which have been the subject of previous several controversies. For that, in situ high-temperature X-ray diffraction (HT-XRD) supported by Fourier transform infrared spectroscopy (FTIR), simultaneous thermal gravimetry and differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM) analysis were used and the combination of results showed that the progressive thermal stress of DCPD in air resulted in a complex heterogeneous formulation consisting of dibasic calcium phosphate anhydrous (CaHPO4, DCPA) and an amorphous calcium phosphate, which appears at low temperatures (~160 °C) and persists up to 375 °C. This amorphous phase was identified as a disordered calcium pyrophosphate (Ca2P2O7, CPP) by the appearance in FTIR spectra of a characteristic band δ(P—O—P) of pyrophosphate groups, located at 740 cm−1. This band is shifted to low frequencies (725 cm−1) as the temperature is increased, indicating the crystallization of the amorphous CPP material into γ-CPP. The high temperature treatment (≥ 375 °C) leads to β−CPP polymorph. The quantification of the amorphous CPP phase by HT-XRD analysis depends on the heating rate of the decomposition of DCPD and presents a maximum at 300 °C for 10 °C min−1. According to the present characterization results, obtaining pure DCPA from the thermal dehydration of DCPD is not effective and leads to biphasic materials including a disordered calcium pyrophosphate phase.

Parametric optimization and analysis of cavitation erosion behavior of Ni-based + 10WC microwave processed composite clad using Taguchi approach

This study aims to develop cavitation erosion-resistant clads on stainless steel (SS-316) using the microwave cladding technique. Ni-based alloy powder (EWAC) was reinforced with tungsten carbide (10% by wt) powder to obtain composite clads. The cladding process was carried out in a domestic microwave applicator of 2.45 GHz frequency with 900 W power. The microstructure, crystal structure (phase identification and quantification), and microhardness of the developed clad were investigated with scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD), and Vickers microhardness tester, respectively. It was found that the deposited clad has a uniform thickness of ∼520 μm, and the microstructure mainly consists of equally dispersed and agglomerated carbides in cellular like Ni-Matrix. XRD analysis reveals that the composite clad was composed of various intermetallic, carbide, and oxide phases. The EWAC + 10WC clad (625 ± 81 HV0.3) has a hardness ∼3.5 times higher than the stainless steel substrate (195 ± 15 HV0.3). The cavitation erosion behavior of the SS-316 and EWAC + 10WC clad was examined by using a vibratory cavitation test apparatus. The parametric cavitation erosion testing was conducted according to the Taguchi L9 orthogonal array (OA) to study the effects of variations in amplitude (AMP), immersion depth (ID), and standoff distance (SOD) on mass loss in SS-316 and composite clad. The parametric study results show that SOD was the most influential test parameter, followed by AMP and ID. SOD contributes more than 50% in the mass loss of SS-316 and clad specimens, whereas AMP and ID contribution was around 32%–37% and 7%–11%, respectively. The developed EWAC + 10WC clad performed ∼6.7 times better than the SS-316. Nevertheless, the SS-316 and EWAC + 10WC clad specimens got severely damage in the form of pits, craters, plastic deformation, lip formation, impingement marks, and secondary cracks.