Surface Topography Of Samples Research Articles

Effect of Bleaching on Surface Roughness and Color Parameters of Coffee-Stained Nanohybrid Dental Composites with Different Viscosities

Abstract Objective The aim of this study was to test the effect of different bleaching protocols on surface roughness, color stability, and translucency parameter of coffee-stained nanohybrid dental composites with different viscosities. Materials and Methods Five nanohybrid dental composites with different viscosities (n = 250)—Neo Spectra LV, Neo Spectra HV, Neo Spectra Flow (Dentsply, Konstanz, Germany), Grandio, and Grandio Flow (Voco, Cuxhaven, Germany)—were used to test surface roughness, color stability, and translucency parameter after bleaching of coffee-stained specimens using either in-office bleaching, home bleaching, or a combination of both. The viscosity of the five types of dental composites was tested using a viscometer. A scanning laser microscope (SLM) was used to examine the surface topography of representative samples from each dental composite after the combined effect of both bleaching agents. Effect of composite type, bleaching protocol, and their interaction was assessed by two-way analysis of variance. For multiple comparisons, Tukey's post hoc test was used with Bonferroni correction. Results Surface roughness of all coffee-stained dental composites increased after bleaching; however, those of Grandio and Grandio Flow increased significantly (p < 0.0001). This was confirmed by SLM images that showed rough surface with protruding fillers after in-office and home bleaching protocol. Results revealed that bleaching, regardless of the protocol, decreased the delta E values of all dental composites; however, it was still higher than the accepted threshold value of 3.7. Neither of the bleaching protocols enhanced translucency parameter of all dental composites. Neo Spectra Flow and Voco Flow had the highest translucency parameter after the three bleaching protocols. Conclusion Bleaching does not improve color stability and translucency of coffee-stained nanohybrid dental composites regardless of the viscosity. Surface roughness of coffee-stained nanohybrid dental composites increases after application of bleaching agents.

A simple and efficient resin precoating treatment on anodised substrate surfaces for enhancing the adhesive bonding strength between aluminium and mild steel

The primary concerns in the adhesive bonding of metal substrate surfaces include inadequate wettability, compatibility, and insufficient mechanical interaction at the bonding interface. These factors are significant barriers to developing and manufacturing high-strength bonded materials. This study utilized three different anodising techniques, such as H3PO4, H2SO4, and NaOH, to produce micro-rough surfaces that improve the adhesive bond between aluminium alloy and mild steel. A novel and a simple method known as resin pre-coating (RPC) were used to increase the wetting and effectively seal the micro-cavities of mild steel and aluminium surfaces. RPC solution comprises 10wt% resin (Absence of hardener) and 90wt% acetone, which facilitated the penetration of resin into the microcavities surface, thereby increasing the bonding surfaces. Subsequently, the normal adhesive mixed with hardener is placed onto the metal surfaces. The adhesive bonding strength was evaluated by conducting the single lap shear test under various surface conditions. The surface topography of anodised samples were examined by X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FESEM), and Contact Angle Goniometer. Experimental results of a lap shear test revealed that the adhesive bond strength of H3PO4 anodised samples is greater than those of H2SO4 and NaOH anodised samples. Furthermore, the RPC treatment increased the bond strength of all H3PO4 anodised samples by 46.91–47.26%, for H2SO4 samples by 39.71–42.22%, and NaOH samples by 37.89–48.51%, compared to the readings obtained without RPC treatment. The combined use of H3PO4 and RPC treatment results in the greatest bonding strength of 16.765MPa, which is 9.17% and 20.10% greater than the bonding strength of H2SO4 and NaOH anodised samples. Thus, the H3PO4 anodised method improved the wetting ability of the metal surface and maximized the use of contact area on the rough substrate surfaces. The anodising treatment details in this study are inexpensive and simple for creating strong adhesive joints in aviation, automobile, and aerospace applications.

The oil lubricated fretting wear behavior under different sliding displacements and frequencies of Ti6Al4V titanium alloy as affected by micro-shot peening

The fretting wear behavior under oil lubricants is of great practical significance since oil is usually used to regulate fretting regime for minimizing wear. In this study, micro-shot peening (MSP) was performed on Ti6Al4V titanium alloy, in which 0.6 MPa injection air pressure, 60 s shot time and high-speed steel particles with an average diameter of 50 μm were used. Surface topography, microstructure, hardness and compression residual stress of test samples were examined. Oil lubricated fretting wear tests were then conducted between titanium alloy sample and GCr15 counterbody under different sliding displacements and frequencies. The test results show that the surface structure of MSP treated samples experienced severe plastic deformation, the surface hardness was increased from 310.8 HV to 433.5 HV, and a compression residual stress of −303.5 MPa was introduced within surface layer. Moreover, MSP treatment reduced the coefficients of friction through producing a micro-dimpled surface. Thereby, the fretting wear resistance of MSP treated sample under oil lubricated condition was improved. By comparison, at higher sliding displacement and frequency, the ability of MSP treatment to resist fretting wear was improved more significantly since more better lubricating effect can be obtained. Fretting damage of untreated sample under oil lubrication was mainly attributed to fatigue wear, delamination wear, abrasive wear and oxidation wear, while that of MSP treated sample was mainly regional peeling off and abrasive wear.

Going Green for Blue - An Indigo Approach

Introduction: Dominating use of chemical processes for reducing indigo at several small-scale production houses formed the ground for initiating this study. Conventional textile processing hubs still use sodium hydrosulphite as a reducing agent irrespective of the source of indigo, whether natural or synthetic ignoring the unfavourable consequences of their disposal and elimination from effluent Method: The paper addresses the critical environmental issues related to the conventional reduction of indigo and studies already undertaken. It examines the indigo dyeing process of cotton using natural, chemical and eco-friendly reducing agents in combination with calcium hydroxide for a comparative study. Identification of natural indigo through High-Performance Liquid Chromatography was undertaken for further experimentation. Under specific parameters, the study examined the effect of Thiourea dioxide and natural reducing agents in indigo dyeing replacing Sodium hydrosulphite. The difference in weight, strength, and colour parameters such as K/S (HUNTERLAB), CIELab values and colourfastness are measured. The experimental results showed weight gain in all fabrics after indigo dyeing. There is a decrease in weft strength only in tamarind, iron, jaggery and dextrose vats. Iron vat showed a higher colour yield out of all reducing agents due to forming metal complexes with the cotton fabric, which influenced colour depth and highest relative colour strength % (114.11) and ΔC (8.48). Result: Thiourea dioxide showed the next highest relative colour strength % (96.59) and lowest ΔH values (8.54) concerning the values of the hydro process. Structural changes of fiber were studied by using SEM (Scanning Electron Microscope) after using different reducing agents, which revealed superior surface topography of samples dyed using thiox. The colour difference showed no significant effect on the colourfastness of alternative reducing agents. Conclusion: Thiox can be a perfect substitution for hydro in indigo dyeing as it was found practical and feasible for implementation even by small-scale units in India.

Experimental investigations on ultrasonic assisted turning of magnesium silicon carbide

ABSTRACT The conventional turning (CT) of Mg-SiC was found difficult due to high tool wear and surface roughness, which reduced the machinability of the composites. In this paper, a study applying ultrasonic vibration assisted turning (UAT) along with minimum quantity lubrication (MQL) is proposed to improve the machinability of Mg-SiC. The input parameters used in this work are spindle speed (SS), feed rate (FR), depth of cut (DOC), and percentage intensity of ultrasonic power (PIUP). The flank wear morphology of the cutting tool and average surface roughness (Ra) of the workpiece is studied. In addition, the surface topography of machined samples was studied by AFM to assess the surface quality. The results show that UAT with MQL reduces the Ra by 21% and 7% compared to CT and UAT at dry cutting conditions. The flank wear (Vb) decreased by 15% compared to dry UAT.

Investigating in-vitro degradation, fatigue behavior, and fracture toughness of electrical discharge-processed Mg alloys for biodegradable implant applications

Biodegradable magnesium (Mg) alloys hold great potential for revolutionizing the field of biomedical engineering by offering temporary support during tissue healing and degrading without leaving permanent residues. However, their clinical applications have been limited due to their relatively high degradation rate. This study focuses on evaluating the in-vitro degradation, fatigue resistance, and fracture toughness properties of Mg alloys under cyclic loading conditions, mimicking real-life scenarios. Wire Electrical Discharge Machining (WEDM) was used to prepare spark-processed Mg samples with complex surface texture, and fine-polished Mg samples were used for comparison. The structural characterization, electrochemical corrosion behavior, degradation assessment, and mechanical integrity of the samples were comprehensively analysed. The results show that the Electrical Discharge processed (EDed) Mg sample exhibited uniformly distributed overlapped craters on the surface, which led to a lower charge transfer resistance and higher corrosion potential compared to the Pristine Mg sample. The rough surface topography and alkaline pH microenvironment of the EDed Mg sample facilitated rapid apatite mineralization, but the resulting Ca-deficient apatite compromised its structural stability. Both EDed and Pristine Mg samples exhibited a significant reduction in fatigue life and lower fracture toughness with prolonged immersion. These findings provide valuable insights into the performance of Mg alloys and their potential applications in biodegradable implants, guiding the design of robust implant materials for enhanced patient outcomes.

Utilization of organoclay amended bentonite for hydraulic barrier applications under adverse electrolyte environment

Inorganic ions such as sodium and calcium are often found in industrial leachates, municipal solid waste leachates and deep geological repositories, which can significantly impact the geotechnical properties of hydraulic barrier materials. Researchers have suggested the utilization of organoclays as landfill liner amendments, especially when the liner is in contact with organic contaminants. This study focuses on the impact of inorganic salts (NaCl and CaCl2) on the geotechnical properties, such as consistency limits, swelling, and hydraulic conductivity of organoclay-amended bentonite (BOC) liners. Different concentrations of salt solutions (0, 0.1 N and 1 N) were selected for the execution of Atterberg limits, free swell tests, and oedometer tests. The surface charge characteristics of bentonite and organoclay were attained with the aid of zeta potential measurements. The variation in the surface topographies of soil samples at different electrolyte conditions was analyzed with the help of scanning electron microscope images. The addition of organoclays significantly reduced bentonite's swelling characteristics and liquid limit due to the unique hydrophobic and organophilic attributes of organoclay but increased the hydraulic conductivity. However, the influence of inorganic salts on the geotechnical parameters of organoclay-amended bentonites showed less variance than that of bentonite. Also, no soil samples exceeded the limiting hydraulic conductivity criteria required for landfill liners, i.e. 1 × 10−9 m/s. Hence, organoclay-amended bentonites could potentially be utilized for hydraulic barrier applications even in an electrolytic environment without compromising the hydraulic conductivity criteria.

Study on the Machining of Duplex Stainless Steel and its Microstructure and Surface Roughness

Duplex stainless steel (DSS) is a relatively new material which is replacing Austenitic steels in offshore and paper-pulp industries due to its excellent combination of mechanical and corrosion resistant property. In this investigation, the work piece material that was utilised was DSS 2205. The experiment is carried out using a vertical CNC milling machine that has three axes of movement. Carbide inserts of ISO grade and ISO geometry APMT1135-PA120 are the types of tools that are utilised for milling operations. To assess the surface roughness values (Ra) of the machined samples, a surface roughness tester with the model number SJ-201 from Surf test was utilised. The investigation of machined DSS specimens using scanning electron microscopy revealed that the surface topography of the machined samples was homogeneously produced with smaller grooves with side flow being seen on the machined surface. According to the outcomes of the experiment that compared cutting speed to roughness, the roughness value decreases proportionally to the increase in cutting speed. The variations of Feed Rate vs. Roughness showed that an increase in the roughness value occurs in conjunction with an increase in the feed rate. The correlation between the depth of cut and the roughness value revealed that the roughness value is directly proportional to the depth of cut.

Application of four-segments annular Silicon drift detector for 3-D surface topography reconstruction by micro-PIXE

Information about the surface topography is very important to achieve the correct elemental concentrations from the 2D X-ray intensity maps in micro-PIXE. Previously, an innovative approach of stereo-PIXE has been introduced to reconstruct the surface topography using two X-ray spectrometers in the lateral direction of the detector positions. Here, we developed the stereo-PIXE method to the four-segment Silicon drift detector (SDD), mounted at the Jožef Stefan Institute (JSI) microprobe, by considering a set of stereovision maps acquired by orthogonal segments to reconstruct the surface topography both in the lateral and longitudinal directions of the scanned area. To this aim, X-ray intensity disparity from the opposing segments was simulated for an ideal flat inclined model of the sample to infer the inclination angle across the opposing segments. Then, the obtained two gradient components of the surface topography from the inclination angles, along the axes that connect the two opposing segments, were reoriented along the scanned area with a proper rotation angle. Thus, to reconstruct the 3-D sample surface topography profile, the integration of the surface topography gradient was numerically performed in the two dimensions along the sample surface. The feasibility of the method is demonstrated on the pure Ti sample with scratched structures.

Experimental study of MQL applicability in ADI grinding and its influence on surface topography

ABSTRACT When workpieces require tight tolerance or a good surface finish, grinding is usually the best solution. Yet this process is characterised by generating a great amount of heat that needs to be controlled. The minimum quantity lubrication (MQL) system emerged as an alternative to the flood cooling system. Nevertheless, the employment of the former in austempered ductile iron (ADI) surface grinding is still an unexplored topic. This research seeks to experimentally study the applicability of MQL and the influence of the wheel speed and workspeed, in the surface topography of ADI samples subjected to different conditions of surface grinding. ADI surface topography was acquired, then the roughness parameters and surface hardness alterations were determined. The results show that the application of MQL in ADI surface grinding is possible. The surface roughness is similar to that of the flood cooling system and the surface hardness alterations are small.

Study of Static Flexural Strength Anisotropy of Yttrium Calcium Oxyborate Crystals

As a promising optical and piezoelectric crystal, yttrium calcium oxyborate (YCOB) has been criticized for its easy fracture during both the cooling and machining processes. Herein, in order to evaluate the mechanical energy (G) required for crack propagation on one crystal plane, we measured the bending strength of the YCOB samples with different orientations via employing a three-point bending test. The surface topography of the polished sample was measured, and the average surface roughness is limited to 10 nm. Fracture surfaces were also observed and analyzed. The results showed that the bending strengths of Y-cut and Z-cut samples were higher than other cut directions in the XZ principal plane, showing obvious anisotropy. It can be found that the cleavage planes (2¯01) and (101) were always observed in fractured samples in multiple directions in the XZ principal plane. The contribution of the cleavage planes (2¯01) and (101) to the fracture of the specimens was discussed in detail by the theorem of energy minimum. Finally, based on the obtained scanning electron microscopy results, we propose the mechanism for crack advance in YCOB crystals. A perfectly brittle crack in a crystal prefers cleavage planes with low surface energy. It is believed that these findings may provide fresh ideas to overcome the cleavage fracture of larger size YCOB crystals.

Prediction of mechanical properties and surface roughness of FGH4095 superalloy treated by laser shock peening based on XGBoost

Laser shock peening (LSP) is a novel metal surface modifying technology, which can enhance the mechanical properties of materials and extend fatigue performance of components evidently. The outstanding mechanical properties induced by LSP occurs through severe plastic deformation, which will cause the surface topography evolution. With the rapid development of artificial intelligence (AI), which provide an effective solution to solve complex problems when with limited experimental data. In this work, FGH4095 superalloy was selected as the experimental material. LSP experiments were conducted with a Q-switched Nd: YAG laser. Laser energy of 4 J, 6 J and 8 J were used with overlap rate of 30 % and 50 %. The residual stress, microhardness and surface topography of experimental samples treated by LSP was investigated. What is more, the AI method based on XGBoost was applied to predict the mechanical properties and surface roughness of FGH4095 treated by LSP. The laser energy, overlap rate, depth were set as input parameters, while the residual stress, microhardness and surface roughness were set as output parameters. The predicted results showed a great agreement with the experimental data. It can be indicated that XGBoost is a suitable method for accurately performing prediction of mechanical properties and surface roughness of materials treated by LSP.

Surface characterization and analysis of textured injection moulded PC-ABS automotive interior components

Automotive interior components are produced by injection moulding due to its cost effectiveness in mass production. The surfaces of these components are textured to control the appearance and other surface functional properties such as wear and scratch resistance. Key challenges lie in replicating the features of mould tool with high aspect ratio which are influenced by the polymer and large number of process variables. Hence, to control the aesthetic properties, it is important to improve the understanding of the replication of textured surfaces and its relationship with measured gloss. In this study, the surface topography of PC-ABS samples is investigated using coherence scanning interferometry. Replication of two types- coarse and fine grain surface texture are investigated to identify the effects of tool temperature, injection speed and holding pressure. Areal surface parameters are scrutinized for the quantitative characterization and discrimination of study samples surface topographies. The correlations between process parameters, measured gloss and areal surface parameters are discussed. The results show significant influence of process variables on the replication of surface topography and measured gloss. The grain pattern governed the set of surface parameters selected and the variation in gloss. The process variables are observed to influence different region or distribution of specific surface features represented by surface parameters.

Differential confocal measurement of microstructure surface topography based on centering error optimization and wavelet threshold denoising

This paper proposes a precise differential confocal measurement method based on centering error optimization and wavelet threshold denoising (DCM-COWD), which can realize non-contact measurement of microstructure surface topography with high precision and efficiency. Firstly, the influence of pinhole diaphragm size and offset on axial response curve is analyzed through multiple experiments to obtain the optimal pinhole diaphragm diameter and offset of the differential confocal measurement system. Secondly, a probe centering method based on grating rotation successive approximation is designed, in order to reduce the centering error of 3D topography measurement during the spiral scanning process. Thirdly, a translation invariant (TI) wavelet threshold denoising algorithm based on median filtering and whale optimization (WOA) is proposed, which can improve the signal-to-noise ratio (SNR) and reduce the root mean square error (RMSE), and effectively suppress the Pseudo-Gibbs phenomenon of discontinuous points. Finally, the surface topography of a standard sample is measured based on DCM-COWD system. The measurement results show that the center error is within 0.75 μm and the maximum deviation is within 1.45 %. The measurement results show high accordance with the commercial white light interferometer, and the processing speed is improved by 4.17 times. The proposed method has great application potential for the precise and efficient measurement of 3D surface topography.

Evaluation of the efficacy of a novel disinfecting material on the surface topography of gutta-percha: An in vitro study.

The effect of chemical disinfection on gutta-percha (GP) has to be closely studied whether it affects surface topography and thereby causes leakage and reinfection of canals. The purpose of the study is to assess the surface topography of GP cones after disinfecting with a novel disinfecting material, graphene oxide (GO), and compare the same with other disinfecting materials, including sodium hypochlorite (NaOCl) and silver nanoparticles (AgNps). After determining the power (0.84) of the study, 48 GP cones were taken and categorized into four different groups based on disinfecting agents. Forty-eight GP cones (ISO size 30 6% taper, DIADENT) were taken and are randomly selected and grouped as follows according to the disinfecting agents: Group 1 - control (untreated GP points, n = 12), Group 2 - NaOCl (n = 12), Group 3 - AgNPs (n = 12), and Group 4 - GO (n = 12), respectively. After treating with the above disinfecting materials, the surface topography of samples was evaluated using atomic force microscopy. The data were analyzed statistically using one-way ANOVA and post hoc (Tukey's honestly significant difference) tests. IBM SPSS (version 21.0) software was used. The tests performed were one-way ANOVA and post hoc. Statistically, significance was set at a P ≤ 0.05. The root means square values and surface roughness values were lesser for the GO group and AgNPs when compared with the NaOCl group, which were statistically significant. Within the limitations of the study, this study had shown lesser surface topography deterioration of GP cones when treated with GO and AgNPs, whereas more deterioration was observed with NaOCl.

Synchrotron Radiation Fourier Transform Infrared (SR-FTIR) spectroscopy in exploring crosslinked chitosan-rice husk bio-composites by gamma irradiation

Chitosan biomaterials have widely been used to absorb heavy metals from wastewater and aquatic system due to their low residue generation and the ability to recycle and reuse adsorbents. The chitosan polymer’s high abundance of amino groups also allows for numerous chemical changes to improve its adsorbent characteristics and adsorption capacity. This work synthesized the bio-composite from rice husk and coated it with chitosan solutions. The gamma irradiation had been applied to create the crosslinking chitosan to join two or more intermolecular or intramolecular by a covalent bonding that could give a more rigid structure and potentially a better-defined shape of the material. The Chitosan-Rice Husk bio-composite was irradiated using gamma radiation at a dose of 50, 100, 200, and 400 kGy. Synchrotron Radiation Fourier Transform Infrared (SR-FTIR) Spectroscopy results revealed the induced crosslinking formation of bio-adsorbents after irradiation. The surface topography and composition of samples were demonstrated by using SEM. The natural bioproduct or waste bioproduct is a new promising adsorbent for the removal of heavy metals from industrial wastewater.

Shale Wettability Characteristics via Air/Brines and Air/Oil Contact Angles and Influence of Controlling Factors: A Case Study of Lower Indus Basin, Pakistan.

Wettability is the fundamental parameter that influences the productivity of hydrocarbon reservoirs. The knowledge of this regarding shale formation is yet inadequate; thus, detailed analysis is essential for successful development of such reservoirs. The Early Cretaceous Sembar formations in the Lower Indus Basin, Pakistan, is considered as the key target for energy exploration; however, it exhibits large uncertainties due to the lack of data availability. Sembar shales hold significant hydrocarbon volumes rich in organic content; however, prior to this, no comprehensive research has been conducted to quantify the wetting behavior of these shales. Thus, precise information about the wetting behavior of Sembar shale formations is essential, as it is influenced by many factors. Therefore, in this study, we examined the wettability of Sembar shale samples by performing a suit of contact angle (CA) measurements. The CA measurements on shale samples were performed using different salt types (NaCl, KCl, MgCl2, and Reef Salt) and concentrations of 0.1 M and 0.5 M under ambient pressures and varying temperatures (25-50 °C). The CA was measured via air-brine and air-oil under prevailing pressure and temperature conditions. Subsequently, the sample morphology and surface topography were examined via field emission scanning electron microscopy and atomic force microscopy, respectively. The mineral compositions were obtained via X-ray diffraction studies. The results clearly show that the Sembar shale possesses a mixed wetting behavior. Under dry surfaces, they have large affinity to oil and deionized water in which the droplet spreads quickly on the sample surfaces. Conversely, the samples aged with n-decane and NaCl brines exhibited higher CAs than the untreated samples. Additionally, the CA measured by changing temperatures led to an increase for all brine droplets; the CA further increased as the concentrations of salts increased from 0.1 to 0.5 M. We then discussed the possible reasons for the discrepancy in CA values due to temperature changes and brine concentrations. Moreover, the CA was measured corresponding to the surface roughness from which it appears that it merely affects the wettability of these shale samples. However, the present study results lead to an improved understanding of the wettability of Sembar shale of the Lower Indus Basin in Pakistan.

Relating Surface Topography to Impedance Behavior in Solder Mask Coated Circuit Boards

To manufacture circuit boards, thin film metallic patterns are first designed and deposited onto FR4 substrates to form the circuit electrodes, followed by a subsequent deposition of a solder mask coat to better insulate the electrodes and prevent cross talking between them. Because this manufacturing process can deposit multiple circuits on the same board, it is often assumed that all circuits on the same electrical circuit board are identical and exhibit similar electrical responses. However, the electrical response of circuit boards is a multi-variate function of solder mask heterogeneity, exposure conditions, humidity, type of manufacturing technique, and sample surface topography among other factors. In this paper, identical circuits on the same solder mask coated board demonstrate a “dual” behavior response in its impedance response; a “high impedance” response and a “low impedance” response as seen in Fig. 1. Although this “high” or “low” behavior can be characterized by the impedance magnitude, the impedance phase angle also provides a means to distinguish the dual behavior responses measured. To gain better insight into the factors that drive the resulting impedance behavior measured, circuit topography was characterized to tie surface roughness parameters to electrical measurements. 3D surface profiling was done on five interdigitated circuits containing 25 pairs of electrodes each. All circuits examined were located on the same board and received no exposure treatment to isolate only the relationship between surface topography and impedance behavior. Each circuit examined showed three distinct regions classified by surface height. The tallest region corresponded to the positive electrode, the second tallest region to the negative electrode, and the lowest region to the solder mask. For each region measured on each interdigitated circuit, the surface roughness parameters were calculated using the Keyence VK-X3000 software and then averaged to represent the overall topography of the respective regions. The impedance measurements were then analyzed in the context of the respective region average height profiles and surface roughness parameters for each circuit to find relationships between surface roughness and electrical behavior. This paper introduces a new approach to understanding impedance behavior of solder mask coated circuit boards with respect to the circuit topography and roughness parameters. Figure 1

Simulation of surface roughness evolution of additively manufactured material fabricated by laser powder bed fusion and post-processed by burnishing

Additively manufactured (AM) metal parts are usually post processed by mechanical surface finishing to attain desired surface roughness. Simulation of AM chain provides means to effectively optimize the final product's quality characteristics in the design stage. The present study developed theoretical models for simulation of surface topography and roughness of parts produced by the laser powder bed fusion (LPBF) process and their evolution after burnishing as post-treatment. The simulation algorithm has been integrated by combining principles of LPBF process, i.e., formation of the melt pool and kinematic of motion, as well as the fundamental theorem of multi-roller rotary burnishing process, i.e., Z-map approach and mechanic of elastic rebound of the surface. This simulation allows the surface topography and roughness to be controlled by adjusting both sequential processes' parameters in a short period with acceptable accuracy. To verify the simulation results, 316L stainless steel was fabricated by an EOS GmbH printing machine and then burnished under different processing conditions. 3D surface profile and surface roughness of as-printed material and those post-processed by burnishing were measured through microscopic examination and surface roughness measurement, respectively. The results obtained through comparison of confirmatory experiments and simulation model affirmed that the proposed approach is accurate enough to predict the surface topography and roughness of as-printed and post-treated samples. The proposed integrated simulation framework has been further utilized to identify how the parameters included in the chain of additive manufacturing and sequential post-processing contribute to achieving nanoscale surface finish in the design stage.

Single-shot optical surface profiling using extended depth of field 3D microscopy.

The measurement of three-dimensional samples at high speed is essential for many applications, either due to the requirement for measuring samples that change fast over time, or due to the requirement of reducing the scanning time, and therefore inspection cost, in industrial environments. Conventionally, the measurement of surface topographies at high resolution typically requires an axial scanning of the sample. We report the implementation of a technique able to reconstruct surface topographies at high resolution, only from the acquisition of a single camera shot, dropping the need to perform an axial scan. A system prototype is reported and assessed as an ultra-fast optical surface profiler. We propose robust calibration and operation methods and algorithms to reconstruct surface topographies of optically-rough samples, and compare the experimental results with a reference confocal optical profiler.