Surface Characteristics Of Materials Research Articles

Impact of land use land cover changes on urban temperature in Jakarta: insights from an urban boundary layer climate model

Urbanization is one of the important drivers of increasing local temperatures. As cities and urban areas evolve, extensive land use and land cover (LULC) changes alter the physical characteristics of surface materials. This modification results in reduced evapotranspiration rates, ultimately contributing to higher surface and air temperatures. This study investigated the impact of urbanization on urban temperature in Jakarta. Urban temperature was simulated for a 20-year time period (1995–2014) by the urban boundary layer climate model UrbClim, using LULC data for both 1995 and 2014. Temperature changes were analysed by assessing the temperature anomaly across different LULC change classes divided into four main classes namely no built-up changes (BB), no green spaces changes (GG), built-up to green spaces (BG), and green spaces to built-up (GB). The study revealed that the conversion of green spaces to built-up areas (GB) had the most significant impact on the increase in air temperature. This was indicated by the mean values of the temperature anomaly of GB of about 0.24°C followed by GG, BB, and BG with the mean values of the temperature anomaly of about 0.20°C, 0.19°C, 0.17°C, respectively. The different temperature anomalies of the LULC change classes indicate that green spaces have an important role in maintaining local climate. Hence, it is important for local government to effectively manage the composition, the quantity, as well as the distribution of green spaces within a city. By looking at temperature anomalies of LULC change classes, the present study provides an alternative approach to many existing methods that provide general information about temperature changes, without specifically analyzing the effects of LULC transformations.

Effect of micropatterning with nanowire-based microcavity array on bacterial enrichment and selective distribution

The micro-patterned topography can affect bacterial enrichment and selective distribution by modifying the characteristics of material surface. In this study, we fabricated microcavity patterned silicon surfaces, and quantitatively explored the amount and distribution of Escherichia coli (E. coli) cells attached on a series of defined topographies. The results showed that E. coli cells enrichment was significantly increased on silicon nanowires-based microcavity array when compared to nanowires patterned silicon wafer. Furthermore, the microcavity diameter can control bacterial distribution by changing hydrophilic performance of interface. With the microcavity diameter of 7 µm, the cells colonized into the microcavity almost in its entirety, whilst distributed around the microcavity completely with 10 µm diameter, regardless of centre distances. This phenomenon can be explained by the Cassie-Baxter model equation according to the wettability. The distribution of bacterial enrichment changed with the silicon surfaces turning from non-wetting status to wetting status when treated with oxygen plasma to modify the hydrophobicity. These results demonstrated that microcavity patterned surface could favor bacterial enrichment on silicon and strictly confined bacterial distribution inside/outside the microcavity. Moreover, the nanowires inside microcavity can also increase electron conductivity and reduce the internal resistance, thus providing scientific evidence for the design of wearable microbial fuel cell with rational optimization and integration of different components for electronic skin.

Human gingival fibroblast response on zirconia and titanium implant abutment: A systematic review.

The peri-implant region, where restoration interfaces with mucosal tissue, plays an essential role in overall implant success and is just as important as osseointegration. The implant abutment materials are in intimate contact with human gingival fibroblasts (HGFs). This study compares the proliferation of HGFs between zirconia and titanium abutments used in dental implants. An electronic search was performed using PubMed, EMBASE, and Web of Science databases. English articles based on in vitro studies testing HGFs proliferation on zirconia and titanium implant abutment materials were included. A quality assessment of the selected study was performed using the web-based Science in Risk Assessment and Policy (SciRAP) tool. The HGFs proliferation and cellular morphology tests on zirconia and titanium materials from the included studies were summarized, exploring the role of material surface characteristics. The electronic search yielded 401 studies, of which 17 were selected for inclusion. Zirconia exhibited comparable or superior efficacy in promoting the proliferation of HGFs compared to titanium. Observations on cellular morphology showed similar outcomes for both materials. Establishing a definitive relationship between contact angle, surface roughness, and their influence on cellular response remains challenging due to the varied methodological approaches in the reviewed studies. Based on the findings of this systematic review, zirconia shows comparable reliability to titanium as an abutment material for HGFs proliferation, with comparable or superior HGFs proliferative outcomes.

An experimental investigation of abrasive jet machining parameters for optimized surface finish of mild steel components

Abrasive jet machining is one of the unconventional machining processes that are initiated for alternations of surface characteristics of ductile materials, like mild steel, due to the entrainment of high-velocity abrasive particles. The present experimental investigation deals with the major process parameters of the AJM process, namely air pressure, standoff distance, and time of machining, on the average surface roughness (Ra) of mild steel specimens. Experiments were conducted on the self-developed AJM setup using aluminum oxide abrasive particles of an average size of 50 µm. The pressure of air is changed in three levels, 6, 7, and 8 bars. The standoff distance is taken as 2 mm constant for all the cases. The surface roughness was measured at machining times of 20, 40, and 45 seconds. The presence of the increase of air pressure from 6 to 8 bars applied for all the machining time showed an increasing influence on roughness, although always significant in Ra. For 8 bars of pressure and 45 s of machining, the minimum resulted in 1.39 µm, compared with 3.47-4.02 µm. The rate of decrease in surface roughness is sharp with increasing machining time from 20 to 40 seconds but marginal beyond that. An optimal machining time of 40–45 seconds was identified to obtain a minimum Ra. Capability of AJM as an effective technique to enhance the surface finish of mild steel components, and practical insight of this study is very useful toward optimization of process parameters for attaining the targeted surface quality. The results obtained may assist in expanding the industrial application of AJM toward the finishing of ductile materials in various manufacturing fields.

Assessment of Various Archwire Materials and Their Impact on Orthodontic Treatment Outcomes.

Aim Orthodontic treatment relies heavily on the mechanical properties and surface characteristics of archwire materials to achieve optimal outcomes. This study aimed to comprehensively evaluate the mechanical properties, including tensile strength, yield strength, and modulus of elasticity, as well as the surface characteristics, such as surface roughness and frictional properties, of different archwire materials. Methods Four types of archwire materials, stainless steel, nickel-titanium (NiTi), beta-titanium, and esthetic archwires, were subjected to mechanical testing and surface analysis, with 31 in each group. Tensile testing was conducted to determine the maximum tensile strength, yield strength, and elastic modulus of each material. Surface roughness analysis was performed using profilometry techniques, and frictional properties were evaluated using an orthodontic friction testing apparatus. Results Stainless steel exhibited the highest tensile strength (900 N), followed by beta-titanium (850 N), NiTi (800 N), and esthetic archwire (750 N). Stainless steel also demonstrated the highest yield strength (780 N), followed by beta-titanium (740 N), NiTi (710 N), and esthetic archwire (650 N). The modulus of elasticity was the highest for stainless steel (200 GPa), followed by beta-titanium (170 GPa), NiTi (150 GPa), and esthetic archwires (120 GPa). Surface roughness was lowest in stainless steel archwires (mean Ra value of 0.25 µm), leading to reduced frictional resistance, whereas esthetic archwires exhibited the highest surface roughness (mean Ra value of 0.40 µm) and frictional forces. Significant differences in the mechanical properties and surface characteristics were observed among the materials (p < 0.05). Conclusions The choice of archwire material significantly influences orthodontic treatment outcomes by affecting the efficiency and effectiveness of tooth movement. Stainless steel and beta-titanium wires are ideal for high-stress applications, providing the robust mechanical strength necessary for complex movements. In contrast, NiTi wires, with their superelasticity, offer consistent and gentle forces, enhancing patient comfort and accelerating the alignment phase. Esthetic archwires, while visually appealing, often compromise mechanical performance, potentially prolonging treatment duration.

A novel use of non-contact methods in analyzing the physical and technical surface characteristics of different materials using electromagnetic measurement techniques

Researchers and industry professionals often use surface metrology techniques to analyze and quantify these surface characteristics, enabling them to make informed decisions about machining strategies and process improvements. This paper presents a comprehensive exploration of surface characteristics of two different materials i.e., C45 steel and brass using electromagnetic measurement techniques. The research used techniques based on: Coherence Scanning Interferometry, Confocal, Focus Variation and Confocal Fusion. Additionally, different light colours were used for these techniques and measurement methods to assess their impact on the quality of mapping the electromagnetic surface. The results demonstrate that the regardless of the colour of the scanned surface (steel or brass), only approximately 50 % of the profile points achieved a 40 % match with the base profile points by scanning with blue light.

Biological, Antifungal, and Physical Efficacy of a Denture Cleanser Formulated with Cnidium officinale Extracts.

We aimed to assess the antifungal efficacy and impact of a denture cleanser containing Cnidium officinale extract on the surface characteristics of denture base materials, as well as its physical and biological properties. The experimental denture cleansers were formulated with C. officinale at concentrations of 100 and 150 μg/mL, combined with 1% cocamidopropyl betaine as a natural surfactant. Antifungal efficacy was evaluated using zone-of-inhibition assays against Candida albicans, revealing inhibition zones of 20 ± 1.8 mm for the 100 μg/mL concentration and 23.6 ± 1.6 mm for the 150 μg/mL concentration. Surface property assessments-including hardness, roughness, color stability, and solubility measurements-demonstrated no significant differences compared to the control group. Biological evaluations included the quantification of polyphenol and flavonoid content. The C. officinale-based cleanser showed significant antifungal activity without affecting the hardness, roughness, color stability, or solubility of denture base materials. Biological tests revealed no cytotoxicity and minimal mucosal irritation. Polyphenol and flavonoid contents were quantitatively measured, revealing higher concentrations in the experimental groups, which were correlated with significant antifungal activity. These compounds are known for their roles in disrupting microbial processes and enhancing antimicrobial effects. These findings suggest that the C. officinale-based denture cleanser effectively inhibits C. albicans while preserving the physical properties of denture base materials. This study highlights the potential of C. officinale in denture cleanser formulations, promoting denture hygiene and oral health. Future research should prioritize long-term clinical evaluations and formulation optimization.

Improving energy harvesting through femtosecond laser surface modification of PVDF/ZnS composite nanofibrous nanogenerators for electronic applications

Surface modification in ceramic/polymer composites holds paramount importance for electronic devices applications. Laser is a versatile and flexible device for modifying the surface characteristics of various materials. Here, we propose a novel approach to enhance the energy harvesting efficiency of polyvinylidene fluoride (PVDF) and zinc sulfide (ZnS) composite nanofibrous membranes through femtosecond laser surface modification. The electrospinning technique is used to produce nanofibers with a high β-phase content in a single step. The PVDF membrane was further enriched with ZnS nanoparticles to enhance the β-phase content. The membranes were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Electron Energy Loss spectroscopy (EELS), and Fourier-transform infrared spectroscopy (FTIR) to characterize their morphological and chemical properties. Femtosecond laser was employed to induce controlled surface modifications, resulting in hierarchical microstructures and surface functionalization. The results showed patterned tracks on the fiber surface while preserving its inherent nature. To validate its utility as an energy harvesting device, the membrane's capability was assessed by measuring the open circuit voltage. The results revealing average output voltages for nanogenerators treated with laser fluences of 0.5 J/cm2, 0.7 J/cm2, and 0.9 J/cm2 are 15.6 V, 25 V, and 17 V, respectively. The maximum output voltage is observed for a laser fluence of 0.7 J/cm2, attributed to the deeper structure created, increasing the surface area of contact and deformation in the structure. This work offers promising avenues for enhancing energy harvesting efficiency and expanding the scope of electronic devices such as sensors and actuators.

Identification of parametric conditions and the influence of laser interaction on the material removal and surface characteristics of 904 L steel super austenitic stainless steel

Identification of parametric conditions and the influence of laser interaction on the material removal and surface characteristics of 904 L steel super austenitic stainless steel

Surface characteristics evolution under the controllable impact cycles of an interrupted discrete waterjet

The interrupted discrete waterjet (DWJ) offers advantages in surface treatment due to its exceptional load characteristics and high controllability. However, the surface characteristics of materials under controllable DWJ parameters have not been fully elucidated. This study delves into the surface morphology, roughness parameters, microhardness, residual stress, and distribution of crystal characteristics in both the depth and radial directions under 2400–36,000 impact cycles of DWJ through peening experiments and material characterization. The findings indicate that the surface morphology is influenced by high-frequency roughness components with limited impact cycles, while low-frequency waviness components gradually take precedence with more impact cycles. As impact cycles increase, certain roughness parameters such as Sq, S5p, S5v, and S10z initially rise until 21,600 cycles, after which they fluctuate within a specific range. Furthermore, DWJ peening leads to an increase in maximum hardness with impact cycles, with the depth of peak value transitioning from the surface layer to the subsurface. The residual compressive stress initially increases and then decreases with impact cycles. Under the experimental conditions, the maximum hardness reaches 268.1HV0.3, a 49.95 % increase from the original state, and the peak residual compressive stress reaches 297.7 MPa with a 310.2 % increase. As impact cycles continue to rise, a balance between material removal and surface hardening is achieved, resulting in the stabilization of maximum hardness and compressive stress as erosion strength grows. Following DWJ peening, there is an increase in the percentage of low-angle grain boundaries, along with enhanced grain refinement, increased geometrically necessary dislocation (GND) density, and the emergence of new phases. As the impact cycles increase, the effects of DWJ peening on crystal grains become more pronounced. Additionally, it has been observed that the lateral jetting influence extends further horizontally than in the depth direction of the incoming jet. It is considered that cyclic hardening and high strain rate effects (1.2 × 104) play significant roles in material hardening and failure.

Chemically accelerated laser processing of SDSS-2507 uniquely under in-situ prepared environments: A comparative study on material dissolution behavior and surface characteristics

Composed of thermochemical reactions, chemically accelerated laser processing (CALP) is a hybrid process that integrates thermal energy with chemical processes. It uses laser activation of material dissolution in chemical environments via localized temperature gradients for streamlined processing, notably for self-passivating materials. This research sheds light on how the dynamic interaction occurs during the fabrication of multiple patterns on SDSS-2507 uniquely by employing an orbit-in-orbit laser positioning strategy in CALP. Current CALP and fabricated surface feature may be useful for micro-reactor applications. So artificial chemical environments (H3PO4, NaCl, and NaNO3) and their concentration, along with controllable laser processing windows like energy and scan factors, were used to simulate actual CALP conditions to study SDSS-2507′s material dissolution and surface characteristics. As SDSS-2507 holds a dual phase with varied thermal characteristics, this article examined each phase’s sensitivity to laser-induced chemical reactions and attacks from aggressive and non-aggressive ions during CALP. In order to acquire insight into the CALP effect on SDSS-2507, phase analysis, surface morphology, CALP-induced crack behavior, surface chemistry, crystallite size, residual stress, mechanical property, and lattice strain were also studied. In the post-CALP, the SDSS-2507′s resistance against aggressive Cl- ions was also scrutinized through electrochemical corrosion analysis. It has been found that, by taking advantage of orbit-in-orbit scan mode during CALP, NaCl exhibited superior performance in terms of material dissolution rate among the three chemical environments, whereas the H3PO4 environment solely performed well in terms of a clean surface without any leftover residue compared to NaCl and NaNO3. In comparison to NaNO3, NaCl, and before CALP, a decrease in crystallite size of up to 22.49%, 19.12%, and 26.23% was also seen. On top of that, when compared to NaCl, NaNO3, and before CALPed surfaces, the corrosion rate was found to be 62.63%, 19.04%, and 35.84% lower, respectively. The findings suggest that, CALP in H3PO4 environment significantly refines the grains compared to B-CALP. This, in turn, stimulates the CALP to somewhat further strengthen the grain boundary and increase its corrosion resistance.

Enhancement of hardness and tribological properties of AISI 321 by cathodic cage plasma nitriding at various pulsed duty cycle

AISI 321, an austenitic stainless steel, has high corrosion and temperature resistance, making it useful for aerospace and chemical processing. Cathodic cage plasma nitriding (CCPN) is a versatile technique that enhances material surface characteristics. This study aims to investigate the effect of the pulsed duty cycle from 10 % to 60 % on microhardness and tribological properties through CCPN treatment. The X-ray diffraction (XRD) analysis indicates a noticeable shift in the γ-phase towards the lower 2θ angle originating from the expanded austenite phase γN by the lattice expansion at the lowest duty cycle. Nitriding at the lowest duty cycle reduced the average crystallite size from 68 nm (untreated) to 4.5 nm, while increasing the duty cycle led to a decrease in micro-strain. The surface microhardness of the sample that underwent the lowest duty cycle improved to 1288 HV0.01 compared to the untreated sample (210 HV0.01). Moreover, the lowest wear rate is observed for the sample nitrided at a low-duty cycle, which agrees with hardness and strain behavior. The results show that the variable pulsed duty in CCPN can improve the surface hardness and tribological properties of AISI 321, particularly at low-duty cycles.

Innovative synthesis strategies for Rambutan-shaped CuNiO2 electrodes in high-performance supercapacitors

The shape/morphology of materials is critical for energy storage, especially in supercapacitors, as it affects their efficiency. The unique Rambutan-shaped CuNiO2 material shows promise for supercapacitors due to its tailored properties. This study stands out for synthesizing the Rambutan-like CuNiO2 structure, further improved by adding Mn, which changes its composition. Using a single-step hydrothermal technique, Mn-doped CuNiO2 (Mn–CuNiO2) is successfully made, with X-ray diffraction (XRD) used to identify phases. High-Resolution Transmission Electron Microscopy (HRTEM) reveals the detailed hexagonal-like architecture of Mn–CuNiO2, shedding light on its nano structural attributes. Brunauer-Emmett-Teller (BET) analysis adds insights into the material's surface characteristics. The electrochemical performance of the Mn–CuNiO2 electrode is thoroughly examined through galvanostatic charge/discharge experiments and cyclic voltammetry, demonstrating its high specific capacitance. Remarkably, the electrode shows a specific capacitance of 1870 F/g at a current density of 1 A/g, highlighting its effectiveness in energy storage. Additionally, the electrode material displays commendable cyclic stability, maintaining superior performance over 10,000 cycles. This durability emphasizes the importance of improving electrode materials to enhance the efficiency and lifespan of supercapacitors, meeting the growing demand for sustainable energy storage solutions.

The Effect of Surface Properties of Different Types of Post Materials on Fracture Type

Introduction and Aim Considering the advantages and disadvantages of different clinical situations, the surface characteristics of the post materials significantly affect the connection of the post material with dentin. In this study, the surface properties of PEEK posts, which are not yet widely used as post materials, were examined in terms of their effects on dentin bonding. Method 66 extracted upper central incisor-type human teeth that had undergone canal treatment with single and straight root canals were used. Posts were produced ) (n=11) from metal, fiber, and PEEK materials to form six groups (CP-0, CP-1, FP-0, FP-1, PP-0, and PP-1). The surface roughness of each post was examined by using a tactile profilometer. Zirconium full crowns, compatible with the central maxillary incisor anatomy, were produced for 66 samples with completed post-core production and polymerized using dual-cure resin cement (Monobond plus Vivadent). Subsequently, the samples were subjected to fracture strength testing at a 135-degree angle to the long axis of the tooth from the palatal side of the zirconium crown at a speed of 0.02 cm/min using a universal testing machine. After the test, the samples were classified into three groups based on the type of fracture: adhesive, cohesive, and mixed. One-way ANOVA and Pearson’s chi-squared tests were used for statistical analysis. Results The surface roughness value of the PEEK post group (1.42 ± 0.21) was significantly lower than that of the metal and fiber post groups. Although no significant difference was found in terms of the fracture type, the adhesive failure rate was higher in the PEEK post group (P

In-vitro fretting tribocorrosion and biocompatibility aspects of laser shock peened Ti-6Al-4V surfaces

Laser shock peening without coating (LSPwC), a prospective surface modification technique for improving the mechanical aspects of Ti-6Al-4V alloy for automotive/aerospace sector, is also expected to dictate the efficiency of this material class for implant application. Here we unravel the impact of LSPwC on Ti-6Al-4V material surface characteristics, in-vitro tribocorrosion and biocompatibility. Micrography shows the presence of nano and sub-micron sized pores after LSPwC process. The role of nano and sub-micron sized pores along with topography modification induced by LSPwC to serve as cues for controlling gene expressions, cell adhesion and activities offer novel insights in this research direction. A detailed X-ray photoelectron spectroscopy analysis detected local chemical non-stoichiometry with reduced number of oxygen diffusion channels. A crucial outcome of this oxide layer modification is the negative skewness (−0.55 ± 0.11) and reduced kurtosis (3.49 ± 0.14) of the surface, along with localized plastic deformation. These factors are correlated with the shift in potential during fretting tribo-corrosion from −800 to −250 mV after LSPwC, accompanied by a lower coefficient of friction of 0.4. Furthermore, the presence of well-spread cells and the up-regulation of beneficial genetic markers (Ki67) on LSPwC surfaces have the potential to form a better bone-material interface. The findings open new frontiers of the LSPwC-treated Ti-6Al-4V surface to synergistically modulate the tribocorrosion and biocompatibility aspects, with exciting possibilities for biomedical implants.

Review on convective and radiation heat transfer between bridges and external environments

The heat exchange between bridges and external environments is the primary cause of the temperature effect on bridges. The complexity of the two-phase (gas–solid) heat transfer mechanism, the diversity of the surface characteristics of bridge materials, and the uncertainties of the environment in which bridges are located make the numerical calculation of the heat exchange between bridges and external environments difficult. Several studies have been conducted by scholars around the world. In this work, the research on convective and radiative heat exchange between bridges and external environments is surveyed, analyzed, and summarized. The influencing factors and calculation methods of bridge temperature are examined, and the convective heat transfer and radiation mechanisms, theoretical calculations, and experimental measurement methods used to investigate the relation between bridges and external environments are summarized and analyzed. The value determination methods for convective heat transfer and radiation absorption coefficients in the calculation of the bridge temperature field are summarized. In addition, the problems and shortcomings of current research are evaluated, and future research directions are identified and discussed.

Investigation of the influence mechanism of hypersonic flow field environment on thermionic emission efficiency

Electron Transpiration Cooling (ETC) is a novel thermal management method that utilizes thermionic emission to cool the leading edge surface of a hypersonic vehicle. Establishing a thermionic emission model that accounts for the hypersonic flow field environment is imperative for accurately predicting the thermal protection efficiency of ETC. A thermionic emission dual-sheath model was established, considering the impact of hypersonic non-equilibrium flow field particle parameters on thermal electron emission. The virtual cathode threshold was obtained through numerical analysis, considering the influence of particles parameters and surface thermoelectric material parameters in a non-equilibrium flow field. Distribution of sheath potential and particle number density in plasma sheath region were performed at a range of conditions. Thermionic emission efficiency approached 80 % as the plasma ion density was 5 × 20 m−3 and the work function was 2 eV. The results showed that plasma ions have different degrees of neutralization effect on thermal emission electrons depending on the flow field and surface material characteristics, ultimately causing varying surface thermionic emission efficiency.

Effect of atmospheric plasma treatment and wet blast on adhesion characteristics of carbon fiber reinforced LM-PAEK thermoplastic composites

Surface characteristics of polymeric materials are quite challenging for adhesion especially thermoplastics, requiring specific surface preparation operations before reaching successful bonding. These processes are principally aimed to increase the low surface energy of the material, bonding agent contact area and wetting characteristics to provide proper and strong adhesion. In this study, two different surface treatments with different processing parameters were applied to CF/LM-PAEK thermoplastic composites in order to examine the changes on surface characteristics and adhesion strengths. Apart from desired surface treatments for thermoplastics indicated in previous studies and backgrounds, wet blasting method is used to prepare surfaces before bonding. Separately prepared surfaces, applying wet blasting and atmospheric plasma treatment, were adhered using epoxy-based film adhesive to be subjected to single lap shear testing to examine adhesion strength under tensile loading. According to the results of experimental study, it was observed that both surface treatments increased the adhesion strength of the bonded pre-consolidated CF/LM-PAEK thermoplastic composites compared to specimens having untreated surfaces.Atmospheric plasma treatment increased the surface energy by 18.24% and showed higher strength up to 14.93% compared to the untreated specimens. On the other hand, surprisingly, wet blasted specimens with lower surface energies showed high strength up to 6.48% compared to the untreated specimens. In addition to surface energies and lap shear strengths, roughness measurements and SEM surface evaluations were also issued to enlighten obtained test results accordingly.

Investigation on Surface Integrity in Milling of Inconel X750: A Comprehensive analysis of Cutting Edges and Machining Parameters

For over a century, machining has been a crucial manufacturing method, with milling standing out as a versatile and effective process for various engineering materials. Ni-based superalloys, renowned for their exceptional properties, present challenges in machining, causing excessive tool wear and surface quality issues. Techniques such as heat treatments, environmental adjustments, and tool geometry alterations are employed to mitigate tool wear and affect surface integrity, crucial for determining the quality of machined work materials, especially in high-strength superalloys where shear deformation induces grain misorientation. In this research article, an experimental study was carried out to find the impact of the different cutting edges on surface integrity while milling Inconel X750. Response Surface Methodology was employed using a central composite rotatable design of experiments to investigate the surface roughness of the machined sample under various cutting conditions. A thorough analysis was undertaken to explore the surface integrity of Inconel X750, involving variations in milling machining parameters (i.e., low, mid, and high) and the utilization of diverse cutting tool inserts. The investigation centred on analysing the sub-surface microstructure, texture, and residual stresses of the machined surface, aiming to achieve a comprehensive understanding of the material's surface characteristics. The double-coated cutting tool T2, with a diameter of 0.8 mm, exhibited superior performance in surface quality and grain distribution, particularly at low cutting parameters (feed rate: 0.15 mm/rev, cutting speed: 35 mm/min, depth of cut: 0.1 mm), showing fine equiaxed and lognormal grain distribution alongside low residual stresses (−36.8 MPa compressive, maximum shear residual stresses: 7.2 MPa) and a surface roughness of 0.17 μm.

Numerical simulation prediction of critical heat flux for 5 × 5 rod bundle with multiple grid spacers and different cladding materials

The critical heat flux (CHF) is one of the safety standards for core thermal design and is crucial for the normal operation of the reactor. The CHF problem of rod bundles with grid spacers is a hot topic in related research. The successful design of grid spacers can improve channel CHF by affecting the flow of downstream coolant, and this detection analysis can be achieved through numerical simulation methods. In addition, most simulation studies have not considered the solid region of the cladding, so there is little research on the effect of cladding materials on CHF. The role of grid spacers in rod bundle CHF is the focus of this paper, and the influence of cladding materials is another discussion direction. In this paper, following meticulous mesh generation and computational model validation, a study on the CHF of the 5 × 5 rod bundle with multiple grid spacers and different cladding materials is carried out by using CFD software. The verification results indicated that the physical model established in this study can reasonably predict the generation location and critical power value in the 5 × 5 rod bundle with grid spacers. Furthermore, the study identified that the grid spacer exerts a significant influence on coolant flow within the channel, while the weakening of the mixing effect of the grid spacer on the coolant flow is the main factor to lead the boiling crisis upstream of the grid spacer. By comparing the effects of thermal properties of different materials on CHF, it was found that when the thermal conductivity ratio of the two materials is 1.08, CHF is almost identical under the condition of a reference heat flux of 0.1 MW/m2 as a step size. In addition to thermal properties, further attention may be paid to the influence of surface characteristics of materials on CHF in future work.