High Level Of Hardness Research Articles

Deposition, microstructure and hardness of AlCoCrFeNi2.1 eutectic high entropy alloy coatings by cold spray, HVOF, and plasma spray

Eutectic high entropy alloys (EHEAs) are reported to exhibit excellent mechanical properties which are useful for coating applications. In this study, we have produced AlCoCrFeNi2.1 EHEA coatings using the cold spray, high velocity oxygen-fuel (HVOF), and plasma spray techniques and compared their bonding characteristics, microstructure and hardness. We observe body-centered cubic (bcc) to face-centered cubic (fcc) phase transformations in all the types of coatings. The high processing temperatures in HVOF and plasma sprays lead to the segregation and depletion of Al from Ni-and Al-rich bcc/B2 regions and form Al2O3. In the cold sprayed coatings, we observe that a fraction of lamellar microstructure is preserved after cold spraying. Regarding the hardness, the cold sprayed coatings exhibit hardness in the range of 440–498 HV due to high work hardening and low oxygen content below 4 at.%; the HVOF coatings show the hardness in the range of 380–556 HV due to the effects of oxide dispersion strengthening with 13–28 at.% oxygen; The plasma sprayed coatings exhibit the hardness in the range 208–258 HV and 6.1–13.4 at.% oxygen. This study demonstrates the feasibility to produce thick and dense EHEA coatings using the above spray techniques, and the cold sprayed coatings exhibit relatively high hardness and low oxygen levels.

A comparative study of self pierceing riveting and mechanical clinch of DP590-Al5754 high-strength steel and aluminum alloys

This paper presents a comparative study of two joining processes, self piercing riveting (SPR) and mechanical clinch, used to join DP590 high-strength steel and Al5754 aluminum alloy. A comparative study of microhardness, tensile shear properties, fatigue properties, and economics of joints from both processes was conducted. The findings indicate that the highest hardness levels are observed in the rivet leg region for SPR joints and in the neck region for mechanical clinch joints. The maximum failure load and energy absorption values of SPR joints were found to be 1.46 and 9.07 times higher, respectively, than those of mechanical clinch joints. The static tensile test results demonstrate that the strength and hardness of SPR joints in aluminum sheets subjected to cold work hardening are significantly lower than those of steel sheets. Therefore, the failure of SPR joints is primarily attributed to the deformation and fracture of the lower aluminum sheet. Mechanical clinch joints fail by neck fracture because the steel sheet neck becomes brittle by cold work hardening and the neck thickness is small. The fatigue behavior of SPR joints was observed to be superior to that of mechanical clinch joints. The findings of the scanning electron microscopy and energy spectrum analysis suggest that fretting wear between the upper and lower sheets results in fatigue fracture of the lower sheet in the joints. When joining the same material on a large scale, the selection of mechanical clinch over SPR can prove an effective method of reducing costs. Furthermore, the selection of a set of dies with an extended life can contribute to the reduction of joining costs.

Assessment of groundwater quality using hydrochemical process, GIS and multivariate statistical analysis at central Rif, North Morocco

This study investigated groundwater in the central Rif region of northern Morocco by analysing 55 water sampling points to assess its physicochemical and hydrogeochemical properties. Through hydrochemical analysis, GIS spatial exploration, and multivariate statistical analysis, a direct correlation was found between EC, TDS, and major ions, influencing overall water mineralization. The key findings included pH levels ranging from 6.10 to 8.52, EC from 828 to 4581 μS/cm, and varying concentrations of Ca2+, Mg2+, Na+, K+, HCO2–, Cl–, N–NO2–, and SO42–. Notably, TDS and TH ranged from 647.19–3609.36 mg/L and 64.23–1051.24 mg/L, respectively, with a significant portion of samples exceeding WHO guidelines, particularly chloride (61.81%), sulfate (92.72%), and nitrate (12.72%) samples. The Piper diagram highlights sodium chlorides (Na–Cl) as the predominant chemical facies (70.9%), while the Gibbs diagram emphasizes the impact of evaporation on water chemistry dynamics. This study revealed the complex influence of geological and anthropogenic factors on groundwater quality, potentially leading to seawater intrusion in coastal aquifers. The observed high mineralization and hardness levels, in addition to mild alkalinity, pose public health risks, underscoring the need for continuous monitoring and sustainable management practices in coastal groundwater management to protect human health and the environment.

Advancing drinking water safety: Facile fabrication of nanofiltration membrane for enhanced antibiotics removal and efficient water softening

Long-term water consumption with contaminated antibiotics and high levels of hardness threatens the health of humans and animals. In this study, a novel positively charged nanofiltration membrane was designed for the dual purpose of efficiently removing antibiotics and softening hard water. The membrane was fabricated by casting P84 polymer solution onto non-woven fabrics, followed by immersion in the polyethyleneimine (PEI) solution for phase inversion and cross-linking, and finalized interfacial polymerization with trimesoyl chloride. Notably, the rapid immersion of the P84 substrate into PEI drastically reduces preparation time by 95 % compared to the regular method while maximizing PEI storage, resulting in uniform pore sizes and a positively charged surface. The optimal membrane showed a high water permeance of 11.3 L m−2 h−1 bar−1 and exceptional antibiotic rejection, i.e., 99.6 % for enrofloxacin, 99.2 % for ciprofloxacin, and 96.3 % for sulfamethoxazole, as well as a highly effective removal in water hardness (over 96 % of Ca2+ and Mg2+) at 4 bar. Simulated water separation tests showed that the optimal membrane effectively controls hard water salinity within optimum drinking water ranges (Ca2+ ≤ 80 mg/L; Mg2+ ≤ 30 mg/L), providing efficient water softening and antibiotic capture ability. Additionally, the optimal membrane demonstrated a superior anti-bacterial and long-term stability performance. This study has significant potential for improving drinking water supply safety and addressing pressing public health and environmental concerns.

Structure, bonding, and properties of RCr6Ge6 intermetallics (R[dbnd]Gd–Lu)

We report the discovery and characterization of three novel ternary compounds: TmCr6Ge6, YbCr6Ge6, and LuCr6Ge6, which complete the series of RCr6Ge6 intermetallics with kagome lattice. Energy dispersive X-ray analysis revealed the off-stoichiometric composition of RCr6Ge6 (RGd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). The powder XRD analysis with subsequent Rietveld refinement showed that investigated compounds crystallize in the SmMn6Sn6 structure type (space group P6/mmm), a disordered variant of the MgFe6Ge6-type, with a small number of vacancies at the rare earth (1a) and germanium (2e) sites and two additional 1b and 2e sites partially occupied by additional rare earth and germanium atoms, respectively. A tendency to structure ordering is observed with decreasing rare earth ionic radii. Electrical resistivity measurements indicate a metallic conductivity type for all studied compounds. Magnetic characterization reveals paramagnetic behavior for TmCr6Ge6 and LuCr6Ge6, respectively, and suggests YbCr6Ge6 as a ferrimagnetic material. The DFT modeling of RCr6Ge6 shows a distinct high electron localization between Ge1 atoms, corresponding to strong covalent bonding. The calculated enthalpies of formation range from −18.56 kJ/mol for Gd to −19.60 for Tm compounds, while the distribution of the density of electronic states (DOS) confirms the metallic type of conductivity for all the series. The calculated elastic properties show brittle behavior and a high hardness level for the whole series. DFT modeling allowed us to reveal mechanisms of RCr6Ge6 formation and the origin of disorder in their crystal structure.

Effects of homogenization and deep cryogenic treatments on microstructure and mechanical property of D2 tool steel fabricated by laser direct energy deposition

The integration of laser direct energy deposition (L-DED) for manufacturing high-hardness D2 tool steel components presents a promising avenue for addressing the increasing complexity of product geometries demanded by modern industry. However, the inherent variability in microstructure and mechanical properties induced by L-DED across the build height necessitates the employment of post-processing techniques to achieve material homogeneity. This study explores the synergistic application of homogenization and deep cryogenic treatment (DCT) as a novel post-processing strategy aimed at mitigating microstructural inhomogeneities and enhancing the mechanical properties of L-DED-fabricated D2 tool steel. Initial analysis of the as-built samples revealed a microstructure characterized by a fine network of eutectic carbides enveloping an FCC matrix, which imposed constraints on martensite transformation during DCT. Homogenization was found to effectively alleviate these constraints, promoting compositional and microstructural uniformity and enabling a more consistent transformation to martensite across the samples upon subsequent DCT. The strategic combination of homogenization and DCT resulted in achieving uniformly distributed high hardness levels exceeding 750 HV throughout the entire sample, regardless of their initial positions within the build. This study demonstrates the potential of combining homogenization with DCT as an effective approach to enhance the structural integrity and mechanical performance of L-DED-fabricated D2 tool steel, offering valuable insights for the development of advanced manufacturing processes for alloyed materials.

Microstructure and mechanical properties of the (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 high-entropy ceramic coating prepared by laser cladding

The (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 high-entropy ceramic coating was fabricated by laser cladding in this study. For the continue and dense coating structure, there were pre-treatments including the squash presetting of feedstock powders and the deposition of Al2O3-TiO2 coating on steel substrate by atmospheric plasma spray. The XRD technology was conducted for investigating the phase transitions during the fabrication of (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 coating. The SEM, EDS technologies and nano-indenter were operated for evaluating the microstructure, composition and mechanical properties of the (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 coating. The results showed that the feedstocks with various structures were successfully transformed into the (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 high-entropy ceramic with rutile structure as well as the formation of intermediate products in similar structures. The (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 coating had a tight combination with the Al2O3-TiO2 coating and showed a thick and compact structure, which included various dendritic crystal structures composed of segregated Al2O3. The (Al1/6Cr1/6Nb1/6Ta1/6Ti1/3)O2 coating exhibited a high level of hardness (13.58 ± 2.05 GPa) and elastic modulus (275.24 ± 32.26 GPa).

A State of the Art on Cryogenic Cooling and Its Applications in the Machining of Difficult-to-Machine Alloys.

Cryogenic cooling has gathered significant attention in the manufacturing industry. There are inherent difficulties in machining materials that are difficult to machine because of high levels of hardness, abrasiveness, and heat conductivity. Increased tool wear, diminished surface finish, and reduced machining efficiency are the results of these problems, and traditional cooling solutions are insufficient to resolve them. The application of cryogenic cooling involves the use of extremely low temperatures, typically achieved by employing liquid nitrogen or other cryogenic fluids. This study reviews the current state of cryogenic cooling technology and its use in machining difficult-to-machine materials. In addition, this review encompasses a thorough examination of cryogenic cooling techniques, including their principles, mechanisms, and effects on machining performance. The recent literature was used to discuss difficult-to-machine materials and their machining properties. The role of cryogenic cooling in machining difficult materials was then discussed. Finally, the latest technologies and methods involved in cryogenic cooling condition were discussed in detail. The outcome demonstrated that the exploration of cryogenic cooling methods has gained prominence in the manufacturing industry due to their potential to address challenges associated with the machining of exotic alloys.

Phase composition, structure and properties of B<sub>4</sub>C–TiB<sub>2</sub> ceramics produced by hot pressing

Composite ceramic materials based on B4C with the addition of TiB2 in amounts of 0, 10, 20, 25 and 30 mol. % have been studied. Titanium diboride was synthesized from TiO2 powder and nanofibrous carbon using the boron carbide method in an induction furnace at 1650 °C in an argon atmosphere. The samples were produced by hot pressing at 2100 °C and 25 MPa in an argon environment. The phase composition was determined, and the apparent density and open porosity of the experimental materials were measured. The microstructure was assessed using optical and scanning electron microscopy. The investigations revealed that an increase in the TiB2 content reduces the open porosity while concurrently enhancing the relative density of the boron carbide ceramics. For a sample containing 30 mol. % TiB2 , the open porosity and relative theoretical density were 1.6 and 99 %, respectively. Using XRD and XRS analyses established that the synthesized materials are comprised of two phases: B4C and TiB2 . The average grain size of TiB2 was 0.85 ± 0.02 µm for the sample with 10 mol. % TiB2 and 8.90 ± 0.25 µm for the material with 30 mol. % TiB2 . It was found that at higher TiB2 concentrations, large clusters of grains are formed. The destruction pattern of B4C grains is intragranular, while TiB2 grains are characterized by intergranular destruction. For a sample containing 30 mol. % TiB2 , the fracture toughness was 4.97 ± 0.23 MPa∙m0.5, and the hardness was 3320 ± 120 HV0.5 . Therefore, the addition of TiB2 at these specified concentrations facilitated a 30 % enhancement in fracture toughness relative to single-phase B4C while preserving a high level of hardness.

Assessing groundwater quality dynamics in Madhya Pradesh: Chemical contaminants and their temporal patterns

Groundwater is essential for maintaining ecosystem health and overall well-being as a pivotal resource for plants and animals. The increasing public consciousness of the deterioration of groundwater quality has emphasized the significance of undertaking extended evaluations of groundwater water quality, particularly in regions undergoing substantial hydrological alterations. This study primarily aims to investigate the spatio-temporal variations in groundwater quality and evaluate its suitability for potable purposes in the region of Madhya Pradesh. The study combines the Mann-Kendall (MK) test and Sen's Slope (SS) to analyze the changes in groundwater quality of all 51 districts of Madhya Pradesh, India, utilizing 12 water quality indices using MATLAB. Data was sourced from the Central Ground Water Board (CGWB) in India from the year 2001–2021. The data was then tested for homogeneity at all 1154 sampling stations using the software XLSTAT. Piper plot clustering characterized the state's groundwater as bicarbonate-calcium-magnesium (HCO3−-Ca2+-Mg2+) type. The study found that the groundwater in the area is heavily impacted by high levels of nitrate and hardness, which is caused by an increase in multivalent cations. The water was classified as ranging from hard to extremely hard, and approximately 25.49% of the state's groundwater has nitrate levels that exceed the acceptable limits. The MK test showed a significant increasing correlation in trends for parameters such as nitrate, sulfate, fluoride, chloride, bicarbonate, total hardness, and electrical conductivity. It also showed a significant decreasing correlation for calcium, magnesium, potassium, and sodium. These results were observed at a confidence level of 95%. The analysis of trends has shown that human-related factors have a considerable effect on the characteristics of groundwater quality. It is therefore recommended that such human-related factors be taken into consideration when developing policies for managing groundwater resources. Consequently, these policies should emphasize the strict enforcement of rules and standards that limit the overuse of fertilizers, ensure the appropriate disposal of municipal solid and liquid wastes, and regulate industrial pollutants.

MATHEMATICAL MODELING OF THE HOLLOW PROFILES FORMING PROCESS

Steel alloys containing manganese and boron are increasingly being used in mechanical engineering, including automotive and agricultural sectors. Products of critical application made from such steels, including hollow ones, have a high level of mechanical properties, surface hardness, and wear resistance. These products are obtained by profiling of previously electrically welded round pipes with a hot sheet stamping or pressure treatment (drawing, cold rolling, stamping). Technological parameters of combined processing methods are determined by the results of experimental research, which, due to the complexity and cost of materials, leads to significant expenses. The application of mathematical modeling can reduce the number of experiments and forecast the quality of finished products. The research focuses on investigating the possibility of obtaining square hollow profiles by means of push-pulling through one stand of a pipe welding unit and defining the requirements for geometric parameters of the billet.

Evaluation of Microstructure and Hardness of AISI D2 Steel by Time Quenching in Comparison with Water and Oil Quenching

Due to an account of its excellent hardness and wear behavior, AISI D2 is used widely in producing of blanking and cold-forming dies, Punches, Shafts, Studs, and Bolts. Increasing toughness at a fixed high level of hardness is growing requirement for this kind of applications. Improving microstructure characteristics, especially carbides distribution by specific heat treatment, is an appropriate way to meet such requirement. The effect of quenching media on microstructure and hardness of pre-heated and austentized (at 980oC) AISI-D2 tool steel has been studied, and hardness and carbides morphology have been investigated. Three different medias, water, oil and water/oil (time quenching) have been used, then all samples were followed by the same tempering 350oC/1 hour. It has been found that the optimal carbides distribution and optimum hardness have been resulted from a time quenching method.

Distribution and Origins of Hardness in Shallow and Deep Groundwaters of the Hebei Plain, China

Elevated hardness concentrations in groundwater have become a noteworthy concern in recent decades because long-term drinking of groundwater with high levels of hardness is an important factor resulting in chronic kidney diseases. In this study, the distribution and origins of groundwater total hardness (TH) in various sub-plains and different land-use areas of the Hebei Plain (HBP) were investigated. A total of 445 groundwater samples in the HBP were collected once in 2021, and twelve chemical parameters, including TH in groundwater, were analyzed. Results showed that TH-rich (>450 mg/L) shallow groundwater in both the central and littoral plains was more than twice that in the Piedmont plain. Similarly, TH-rich deep groundwater accounted for about 18% in the central plain but was negligible in the Piedmont plain. In the Piedmont plain, TH-rich shallow groundwater in urban areas was twice or more than in other land use types. By contrast, both TH-rich shallow and deep groundwaters in agricultural areas in the central plain were higher than those in rural areas. This was opposite to TH-rich shallow groundwater in the littoral plain. In the Piedmont plain, TH-rich shallow groundwater was mainly attributed to water-rock interaction, groundwater over-extraction, and the infiltration of domestic sewage and animal waste. In the central plain, both TH-rich shallow and deep groundwaters likely ascribed to the evaporite dissolution and seawater intrusion. By contrast, the leaching of agricultural fertilizers resulting in the dissolution of Ca-rich and Mg-rich minerals in the vadose zone was mainly responsible for the occurrence of TH-rich shallow groundwater in the littoral plain. Therefore, in order to limit elevated hardness concentrations in groundwater in the HBP, limiting shallow groundwater extraction and strengthening the supervision of the domestic sewage and animal waste in the Piedmont plain are recommended. Besides, restricting the use of nitrogenous fertilizers in the littoral plain is also recommended.

Health Effects of Consuming Artesian Water Supplied through the Centralized Distribution Network in the Population of Arid Areas of the Saratov Region

Introduction: Statistics show that over 11 million Russians use untreated tap water noncompliant with safety standards. Consumption of such water may have adverse human health effects and pose risks of various diseases. The objective of this study was to investigate the relationship between consumption of artesian tap water sourced from centrally operated water supply systems in arid areas of the Saratov Region and the prevalence of cardiovascular, urogenital, and digestive diseases in the local population. Materials and methods: We examined 127 artesian water samples collected from the centralized water supply systems in three arid areas of the Saratov Region in 2008–2022. The water quality was tested by atomic absorption spectrometry, photoelectric photometry, inductively coupled plasma atomic emission spectrometry, and capillary electrophoresis. Data on the residents receiving follow-up care for genitourinary, digestive, and circulatory diseases were obtained from the Saratov Medical Information and Analytical Center. The Statistica 10 software was used for data analysis. Results: We observed high levels of total hardness (24 ± 3 mg-equiv./L), alkalinity (7.5 ± 0.2 units), total mineralization (2,454 ± 546 mg/L), nitrate salts (99 ± 23 mg/L), chlorides (1,610 ± 462 mg/L), sulfates (753 ± 64 mg/L), as well as ions of manganese (up to 11 MPC), magnesium (up to 8.8 MPC), and iron (up to 10.83 MPC) in artesian water samples tested showing noncompliance with tap water quality requirements. We also established that daily calcium intake with tap water (1,403.5 ± 199.5 mg/day) exceeded the recommended one. We established a strong correlation (r = 0.931, r2 = 0.867, p < 0.001) between the mean daily consumption of non-conforming artesian tap water (1.4 ± 0.01 L/day in the Fedorovsky district, 0.7 ± 0.01 L/day in the Novouzensky district, and 0.1 ± 0.01 L/day in the Alexandrovo-Gaysky district) and the proportion of residents of the arid areas of the Saratov Region followed up for diseases of the genitourinary system (1,266 ± 64.3, 1,691.4 ± 107.8, and 758.4 ± 18.1, respectively). Conclusions: Our findings show the necessity of improving measures aimed at raising the quality of water supply in arid areas, including the development of additional measures for preliminary water treatment, and importance of tap water quality control for prevention of adverse health outcomes related to chronic exposure to waterborne chemicals.

Fatigue Analysis of Steering Knuckles Using the Local Strain Approach

The study investigates the mechanical properties and fatigue behavior of steering knuckles used on commercial vehicles. The steering knuckle is made of hot forged bainitic steel (18MnCrMoV6-4-8), which is known to demonstrate high levels of fatigue strength, toughness, and hardness. The local strain concept was adopted to assess the durability of the steering knuckle based on the stabilized cyclic material behavior. For this purpose, experimental investigations have been conducted on both the steering knuckle as well as fatigue specimens under constant and variable amplitude loadings. The fatigue specimens were removed from the area next to the crack initiation location, to represent the microstructure in the critical area of the component. Fatigue life estimations were performed under different load ratios using the FKM guideline nonlinear, employing damage parameters PRAM and PRAJ. The assessment enables a fatigue strength assessment for the steering knuckle by considering the local non-linear material behavior. The estimations of the material's fatigue lifetime using the FKM guideline nonlinear approach were unsatisfactory.

Manufacturing and Characteristics of Hardness Controllable Epoxy for Restoration of Earthenware

Fatty acids, tall-oil, reaction products with tetraethylenepentamine and 1-(2-aminoethyl) piperazine-based epoxy resin were mixed to manufacture 2 types of hardener to enable hardness control for restoration of earthenware. The mixed epoxy resin was manufactured in 2-solution reaction hardening type to control the hardness in the range of approximately 40∼65 Hs, and tensile strength in the range of 27∼121 kgf/mm<sup>2</sup> and hardening type of 20∼30 min were secured. Moreover, it has wear rate that has been enhanced by 2 folds compared to the existing restoration material, which can be controlled in accordance with the mixing ratio, and was manufactured to enable mixing of diversified fillers later on. These results indicate that this is a restoration material that can solve the problems pointed out for the earthenware restoration materials such as processability and workability that occurred due to high level of hardness, tensile force and adhesion strength, etc., and increase in the level of fatigue due to tension with earthenware surface, etc. Accordingly, it is deemed that it is a material that can be used in actual restoration.

GROUND WATER QUALITY AND ITS IMPACT ON HUMAN HEALTH IN DUNGARPUR DISTRICT OF RAJASTHAN, INDIA

Abstract. Dungarpur, one of the most backward districts of India, is a predominantly tribal region of Rajasthan state. Ground water is the major source of drinking water in the region. High concentrations of Fluoride (F) and Iron (Fe) have been reported in the region which poses high risk of rampant water-borne diseases. This study evaluates the ground water quality for drinking purpose in terms of 10 hydro-geochemical and two biological parameters in context of causative factors like land use and geology of the region. The occurrence of water borne diseases in resident population has been examined in association with quality of drinking water and priority areas for policy intervention have been identified. Water samples have been collected from 173 drinking water sources and 346 households consuming water from the selected sources have been surveyed for prevalence of water borne diseases. Water quality surfaces have been mapped in terms of F, Total Dissolved Solids (TDS), Hardness, Fe, alkalinity, Faecal Coliform (FC), E. Coli, and Water Quality Index (WQI) computed on the basis of 10 geochemical parameters, using Inverse Distance Weighted (IDW) method. Results reveal that the north-eastern part comprising Aspur, Sabla and part of Sagwara tehsils predominantly has ‘very poor’ to ‘unsuitable’ water quality. The western part has excessive faecal contamination. Entire district has high levels of TDS and hardness, while excessive Fe and F occur in specific regions. Disease incidence closely corresponds to the geochemical and microbial composition of water. Higher values of WQI correspond with occurrence of Phyllites and Mica Schists.

Investigation of Friction Hydro-Pillar Processing as a Repair Technique for Offshore Mooring Chain Links

Repairing links of offshore mooring chains has presented a significant industry challenge, primarily arising from modifications in material properties, encompassing alterations in microstructure, hardness, and residual stress. In this context, the present work investigates the method of friction hydro-pillar processing (FHPP) applied to R4 grade mooring chain steel. Joints in as-repaired and post-weld heat treatment (PWHT) conditions were subjected to residual stress (RS) tests using the neutron diffraction technique, microhardness mapping, and microstructural evaluations. The process generated peaks of tensile and compressive stresses in different directions and hardness below that of the parent material in the softening zone. The friction zone promoted high hardness levels in the thermo-mechanically affected zone (TMAZ) with a maximum of 19% of the ultimate tensile strength of the parent material. As expected, the PWHT restored the RS and reduced the hardness; however, 4 h PWHT allowed the elimination of a hardness higher than that of the base material.

A diamond double-sided strip detector for alpha-tagging in associated particle imaging

- In associated particle imaging, neutrons from deuterium-tritium fusion are used to interrogate objects of interest. The associated particle imaging technique utilizes an alpha-tagging sensor in the neutron generator to detect the alpha particle that is emitted antiparallel to the neutron, providing neutron birth time and direction. This technique of neutron imaging and induced fission imaging can provide higher contrast image reconstructions and better estimations of fissile material mass than passive measurement techniques. The performance goals of an alpha-tagging sensor in associated particle imaging are a 700-ps timing resolution, a 0.5 mm spatial resolution, high level of radiation hardness, low sensitivity to X-rays, high signal-to-noise ratio, and survivability in the high temperature bake out of the neutron generator. Currently employed YAP scintillators are overwhelmed by the intense X-ray field in the neutron generator, requiring a new alpha tagging sensor design to be developed. We have developed and tested a diamond double-sided strip detector as a proposed sensor for associated particle imaging. Diamond is radiation hard, has a low sensitivity to X-rays, fast timing capabilities, high signal-to-noise ratio, and can withstand the temperatures of bake-out. The spatial resolution can be accomplished with a charge division readout and double-sided strip design. We measured the timing resolution of a single crystal chemical vapor deposition (CVD) diamond with a Cividec C6 charge amplifier readout by measuring the time-of-flight of 241Am alpha particles between a thin plastic scintillator and the diamond. We also fabricated a polycrystalline CVD diamond double-sided strip detector with charge division readout to test the spatial resolution of the design. We found that the detector met both the 700-ps timing resolution and the 0.5 mm spatial resolution goals (both reported as FWHM resolution).

Mechanical, Tribological, and Corrosive Properties of NbCrCx and NbCrCxNy Coatings with Various Nitrogen and Carbon Contents

CrC and NbC carbide coatings both have good mechanical properties, wear resistance, and corrosion resistance. The present study seeks to combine the two coating systems in order to further enhance their properties. NbCrCx and NbCrCxNy coatings (where x and y denote the atomic percentages of carbon and nitrogen, respectively) were deposited on SKH51 substrates using a radio-frequency unbalanced magnetron sputtering system. The mechanical, tribological, and corrosive properties of the coatings were investigated and compared. Among the NbCrCx coatings, the NbCrC61 coating showed high levels of hardness, excellent adhesion strength, and good wear resistance. Among the NbCrCxNy coatings, the NbCrC55N5 coating showed high adhesion strength and hardness and excellent tribological properties. However, for nitrogen contents greater than 16 at%, the adhesion strength was dramatically reduced, resulting in poor tribological performance. Among all of the coatings, the NbCrC49 coating showed the best corrosion resistance due to its enhanced crystallinity, high adhesion strength, moderate surface roughness, and high sp3 C-C bonding ratio.