YAG Fiber Research Articles

Study on microstructures and mechanical performance of laser transmission welding of poly-ether-ether-ketone (PEEK) and carbon fiber reinforced PEEK (CFR-PEEK)

The reliable assembly of poly-ether-ether-ketone (PEEK) and carbon fiber-reinforced PEEK (CFR-PEEK) is crucial to effective load transfer within lightweight and high-stiffness structures, which are commonly demanded in aeronautical, automobile, and medical industries. In this work, laser transmission welding of PEEK and CFR-PEEK has been performed by using a 1070 nm Nd:YAG fiber laser. The effects of process parameters including laser power, laser scanning speed, and clamping pressure on joining quality have been investigated via mechanical, morphological, and thermal characterization. Results show that strong bonds have been formed by entanglements of polymer chains at the joining interface and the mechanical embedment between carbon fibers and PEEK. The formation mechanisms of bubble defects have been classified into three types. One of them was eliminated by scanning the joints twice, which significantly improved joints' mechanical performance and hermeticity with the maximum joining strength reaching 11.6 MPa. Also, a comparative study between PEEK/PEEK and PEEK/CFR-PEEK joints shows that the existence of carbon fibers within the CFR-PEEK significantly increased joints' decomposition threshold, joining region, and strength due to their great thermal conductivity. Besides, the influence of the welding process on the crystallinity of PEEK was analyzed, which was then improved from 11.7% to 34.1% through annealing.

Thermal Injury and Laser Efficiency with Holmium YAG and Thulium Fiber Laser-An In Vitro Study.

Objective: To evaluate using an inanimate model the thermal injury and laser efficiency on high frequency, high energy, and its combination in hands of junior and experienced urologists during holmium YAG (Ho:YAG) and Thulium fiber laser (TFL) lithotripsy. Methods: A Cyber: Ho 150 WTM and Fiber Dust TFL (Quanta System) with 200 μm core-diameter laser fibers (LF) were used in a saline in vitro ureteral model. Each participant (five junior and five experienced urologists) performed 32 sessions of 5-minute lasering (125 mm3 phantom BegoStones™), comparing four modes (3 J/5 Hz [1.5 W], 0.3 J/20 Hz [6 W], 1.2 J/5 Hz [6 W], and 1.2 J/20 Hz [24 W]). Transparent tip and cleaved LF, and digital and fiberoptic ureteroscopes were also compared. Ureteral damage was classified in a scale (0-5) according to the burns and holes seen in the ureteral model's surface. Results: High-power (HP) setting (24 W) was associated with higher delivered energy and higher ablation rates (ARs) in both lasers (p < 0.001). For the same power setting (6 W), there was no difference in delivered energy or stone ARs. Regardless the settings, a higher AR was observed with TFL than with Ho:YAG (0.5Δ mg/s ± 0.33 vs 0.39 Δmg/s ± 0.31, p = 0.002) laser. Higher mean AR was found with cleaved tip vs transparent tip (p = 0.03) in TFL. For both lasers, higher ureteral damage was observed in the 24 W group (p = 0.006) and in the junior urologists (p = 0.03). Between 6 W groups, different types of lesions were found and junior urologist have more lesions when high frequency was used, for both Ho:YAG (p = 0.05) and TFL (p = 0.04). Conclusion: More stone ARs and reduced operative time are observed in HP settings; however, more ureteral thermic-related damage is produced. When comparing the same power, higher energy or frequency does not modify the AR. Nonetheless, more ureteral thermic-related thermal damage is observed in high-frequency settings in unexperienced hands.

Study of the notch fatigue behaviour under biaxial conditions of maraging steel produced by selective laser melting

The current work aims to characterise the fatigue behaviour of an additively manufactured maraging steel, AISI 18Ni300. This is a class of high-strength steel widely used in biomedical, aircraft, aerospace, offshore, and military industries thanks to its good performance in terms of strength, toughness, ductility, dimensional stability, and weldability. Laser-beam powder bed fusion (additive manufacturing) is used to fabricate this type of steel and endows it with properties that make it an excellent candidate for producing prosthetic parts, thereby facilitating a reduction in manufacturing material consumption, labour, and machining time. Given the wide range of loads biomedical components are often subjected to, the current study focused on the multiaxial behaviour of this type of steel. To this end, Fatemi–Socie (FS) and Smith–Watson–Topper (SWT) critical plane methods combined with the theory of critical distances were applied to predict the fatigue life and cracking orientation of this material, with and without notches, under three biaxial loading scenarios. Cylindrical specimens were used and these were fabricated on the base plate in the vertical orientation using a linear printing system equipped with a Nd:YAG fibre laser. The building strategy involved the deposition of 40 μm thick layers at a scan speed of 800 mm/s. The two critical plane models returned good results at low life cycle fatigue but the FS model obtained better results at high life cycle fatigue. Regarding the crack angles, SWT model produced the best predictions.

Propagation of notch fatigue cracks on maraging steel under biaxial conditions

The current work aims at characterizing the fatigue behaviour of an additively manufactured maraging steel. This is a class of high-strength steels widely used in aircracft, aerospace, offshore and military industries thanks to its good performance in terms of strength, toughness, ductility, dimensional stability and weldability. Fabrication of such steel via laser-beam powder bed fusion (additive manufacturing) makes it an excellent candidate for producing prosthetic parts because of its properties, offering a reduction in manufacturing material consumption, labor and machining time. The study is focused on the multiaxial behaviour of the steel, given the wide range of loads often existing in biomedical components. To this end, different critical plane methods are used to predict the fatigue life and the cracking orientation under several biaxial loading scenarios. Thickness effects were also evaluated. Cylindrical specimens were used and these were fabricated in the vertical orientation on the base plate, using a linear printing system equipped with a Nd:YAG fibre laser. The building strategy comprised the deposition of 40 μm thick layers at a scan speed of 80 mm/s. The results are useful to understand the predominant failure mode and the type of critical plane method that is most convenient for such material.

Unconventional milling of zirconia-based bioceramic material with nanosecond pulsed laser

Fabrication of dental restorations made of zirconia-based biomaterials with enhanced mechanical and tribological properties together with customized surface topography and microstructure for promoting enamel adhesion and cell proliferation while hindering bacterial spreading is a very challenging task to accomplish through conventional machining operations. In fact, traditional milling processes of sintered ceramics are typically labor-intensive, therefore expensive and time-consuming, and these aspects can be further exasperated when microsized features are required. On the other hand, unconventional techniques such as laser milling can represent a suitable solution to produce miniaturized individualized structures on advanced ceramics since it is a non-contact thermal process that ensures the elimination of cutting forces and allows hard and brittle materials to be machined without the need for special equipment which requires high investments and long processing times. In this context, this study aims to investigate the capability of a nanosecond pulsed fiber laser to machine samples made of yttria-stabilized zirconia through a systematic experimental approach in order to identify the most suitable process operational parameters combinations that ensure the obtainment of specific surface topographies while minimizing the machining time. The milling process is carried out by using a 30 W Q-switched Yb:YAG fiber laser by controlling laser beam scan speed, scan strategy and hatch distance and following a multi-level factorial design-based experimentation. The adoption of the laser technology to machine yttria-stabilized zirconia results in a high-repeatable, accurate and time-saving process allowing easy control of the process outcomes.

En bloc resection for nonmuscle-invasive bladder cancer: selecting a proper laser.

To discuss the most recent surgical lasers that have been made available to us and to evaluate their potential in performing en bloc resection of nonmuscle invasive bladder cancer. Laser en bloc resection of bladder tumors (ERBT) can be performed with a number of laser systems including Ho:YAG, GreenLight, diode, Tm:YAG and thulium fiber lasers (TFL). The data that is currently available suggests that the water-targeting devices (utilizing water as a primary chromophore - Ho:YAG, Tm:YAG, TFL) may have a number of advantages over hemoglobin-targeting systems (potassium titanyl phosphate:YAG, lithium triborate:YAG). One recent addition to the surgical armamentarium Moses effect enhanced Ho:YAG and the TFL (being able to work both in quasi-continuous and SuperPulsed modes) necessitates careful discussion and comparison with the other available devices. The majority of available lasers have proven to be safe to use and compared to electrocautery allow for lower rates of obturator nerve reflex and result in fewer bleeding complications. The minimal penetration depth and decreased peak power of Tm:YAG and TFLs render them the devices of choice when it comes to ERBT. Unfortunately, more studies on ERBT with TFL are needed in order for us to make a sound assessment of the respective pros and cons.

A Study on the Fiber YAG Laser Welding of 304L Stainless Steel

This work aims to optimize the main YAG fiber laser parameters to weld 304L stainless steel plates of 3 mm thick. Different laser powers (2500, 2000, and 1500 W) and speeds (60, 40, and 20 mm/s) were used and merged in heat input, maintaining the defocusing distance at –2 mm to get full penetration. The weld quality and the effect of the laser heat input on the microstructures of the weld and heat-affected zones were investigated. Besides, the fracture strength of the welded joints and hardness distribution through the cross-sections were evaluated. The weld width has a direct relationship with heat input. The laser power of 2800 W produced full penetration joints without any macro defects while reduction in laser power pronounced partial penetration defects. The size of the heat-affected zone in all the processing parameters was very small. The microstructure of the weld zone shows columnar dendrite austenite grains with small arm spacing in most of the welded zone. The size of the dendrites became finer at lower heat input. At a higher heat input, a reasonable amount of lathy equiaxed grains with some delta ferrite occurred. A small amount of delta ferrite was detected in the heat-affected zone, which prevented the crack formation. The hardness of the weld metal was much higher than that of the base metal in all processing parameters and it has a reverse relationship with the heat input. The fracture strength of the welded joints was very close to that of the base metal in the defect-free samples and it increased with decreasing the heat input.

Effect of high-temperature preheating on pure copper thick-walled samples processed by laser powder bed fusion

The Laser Powder Bed Fusion (LPBF) also called Selective Laser Melting technology uses for the layer-based part fabrication laser beam as the main energy source for melting a powdered material. The processing of pure copper by LPBF technology is a challenge due to its high laser beam reflectivity, thermal conductivity and affinity to oxygen. Thus, for reaching homogeneous sample in an acceptable quality a high power Nd: YAG fibre laser sources are used. In this study, the effect of Nd: YAG fibre laser with a maximum power of 400 W and 400 °C high-temperature base plate preheating as another heat source on the relative density of pure copper thin-walled and thick-walled samples was investigated. Moreover, the effect of layer thickness, laser speed, laser velocity, hatch distance, sample width, scanning and remelting strategy was studied. Further on, the effect of powder bed preheating on the copper powder melting, laser beam reflectivity, wetting and solidification conditions and powder and part oxidation was discussed. Using the statistical methods for experimental planning the behaviour of each observed process parameter was revealed and the proper combination of process parameters was stated. It was found that for reaching relative density over 99% the process parameters should be set from observed range as following: layer thickness 0.03 mm, laser power 400 W, laser velocity 505 mm∙s−1, hatch distance 0.06 mm and powder bed preheating of 400 °C. Despite the high value of relative density, the issues connected with layer and track bonding attributed to thin oxide layers were not successfully eliminated.

Dusting Efficiency of a Novel Pulsed Thulium:Yttrium Aluminum Garnet Laser vs a Thulium Fiber Laser.

Background: Holmium:yttrium aluminum garnet laser (Ho:YAG) is still considered the gold standard in laser lithotripsy. There is a large body of literature comparing the capabilities of Ho:YAG and thulium fiber lasers (TFLs). The novel, pulsed thulium:yttrium aluminum garnet laser (p-Tm:YAG) evaluation model has only been compared with Ho:YAG in terms of its dusting performance to date. It was this study's aim to compare the p-Tm:YAG's dusting efficiency with that of a chopped TFL. Materials and Methods: During the laser ablation procedure, while the laser device was emitting light, the laser fiber was spiraled across the surface of a uniform kidney stone model via software. We relied on the stone model's difference in weight before and after the dusting procedure to assess the dusting efficiency and assessed each laser device's dusting efficiency at various preset laser configurations and laser fiber-motion speeds. We compared both laser devices' laser configurations, which were identical in pulse energy and frequency, while keeping in mind that the pulse duration differed significantly. In addition, we tested each laser device's capability. Results: The average ablated weight across all laser configurations was 0.61 g (standard deviation [SD] = 0.44 g) for p-Tm:YAG and 0.76 g (SD = 0.51 g) for TFL. After statistical analysis, we found no significant difference in ablated weight between the laser devices (U = 1715.5, p-value = 0.11). The maximum permissible frequency configuration for TFL was 1600 Hz, which resulted in the worst overall dusting output. Conclusions: We observed that the p-Tm:YAG's dusting efficiency resembled that of TFL in the identical pulse energy and frequency laser configurations. The ablation efficiency did not seem to be affected by the laser devices' differences in pulse duration. Slower laser fiber-motion speeds resulted in more efficient ablation. When using the maximum preset frequency and power configuration, TFL's dusting efficiency appeared to be inefficient.

Laser induced surface enhanced Raman scattering of silver thin films decorated with carbon nanoparticles

Silver (Ag) thin films decorated with carbon nanoparticles were achieved by ablating Ag/C thin film with an Nd:YAG fiber pulsed laser under the environmental conditions. The structure and optical properties of the Ag/C samples were investigated. In this study, the Surface plasmon resonance (SPR) wavelength of Ag/C samples shift from 457 nm to 527 nm was realized using a different laser scanning rate. Compared to Ag samples, Surface enhanced Raman scattering (SERS) of Ag/C samples was also observed due to decorating with nano-carbon, which demonstrates good steadiness and high SERS intensity with the concentration of Rhodamine 6G (Rh 6G) with 10−5 mol/L. In additional, the simulation results of finite-difference-time-domain (FDTD) verify SERS performance.

PD54-08 HOLMIUM:YAG (HO:YAG) VERSUS THULIUM FIBER LASER (TFL) FOR TREATMENT OF UPPER URINARY TRACT CALCULI IN DUSTING MODE: A CLINICAL COMPARISON OF EFFICIENCY, EFFICACY AND COSTS EFFECTIVENESS

You have accessJournal of UrologyStone Disease: Surgical Therapy IV (PD54)1 Sep 2021PD54-08 HOLMIUM:YAG (HO:YAG) VERSUS THULIUM FIBER LASER (TFL) FOR TREATMENT OF UPPER URINARY TRACT CALCULI IN DUSTING MODE: A CLINICAL COMPARISON OF EFFICIENCY, EFFICACY AND COSTS EFFECTIVENESS Ahmed Ghazi, Mahmoud Khalil, Changyong Feng, Scott Quarrier, and Rajat Jain Ahmed GhaziAhmed Ghazi More articles by this author , Mahmoud KhalilMahmoud Khalil More articles by this author , Changyong FengChangyong Feng More articles by this author , Scott QuarrierScott Quarrier More articles by this author , and Rajat JainRajat Jain More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002081.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Preliminary studies have demonstrated the superiority of TFL compared to Ho:YAG for dusting of urinary calculi. These are mainly based on laboratory studies with emerging clinical reports limited to optimizing TFL dusting settings. We aim to compare the efficiency, effectiveness and costs effectiveness of high power Ho:YAG (100W Empower, Olympus) to TFL (Soltive PLS, Olympus) lasers operated at a fixed dusting protocol. METHODS: A prospective study of 62 patients (31 per group) with 10–30 mm renal calculi was completed. Fixed dusting settings (0.4J X 60Hz) during retrograde intrarenal surgery (RIRS) lithotripsy was used for both lasers. Laser on time (LOT), Ablation efficacy (J/mm3) and Ablation speed (mm3/second) were calculated. Retropulsion, visibility, and bleeding during RIRS were graded by 3 urologists using 5-point Likert scales. Stone-free rate (SFR) was assessed at 1 month with non-contrast CT. Projected cost savings were calculated utilizing the formula [average LOT difference x $100/minute billed to insurance for RIRS minus $178 differential between list price of the 200m TFL ball tip and regular Ho:YAG fiber plus price differential for upgrade to PLS Soltive ($18800/1000) amortized over 1000 procedures=$18.8]. RESULTS: Mean age, BMI, stone number, density, ellipsoid stone volume and STONE score was not significantly different among both groups (Table 1). TFL lithotripsy had significantly shorter LOTs (380.6 vs 533.6 seconds, p=0.015) and higher SFRs (68% vs 34.8%, p=0.03). Both ablation efficacy (21.2 vs 12.5 J/mm3, p=0.02) and speed (4.1 vs 1.2 mm3/second, p=0.003) were significantly higher with TFL. TFL was 2.6 min faster for all stones (3.4 min for stones <15mm vs 1.7min for stones >15mm) with an overall projected $69.2 saving per case [$266- ($178+ $18.8) (Table 1). TFL was superior in terms of retropulsion (1.6 vs 2.8), visibility (1.8 vs 3.3) and bleeding (1.1 vs 1.9) gradings. CONCLUSIONS: This clinical study demonstrates TFL as a more effective, efficient and cost effective laser during RIRS lithotripsy when operated in dusting mode, producing higher stone ablation rates and speed with improved stone free rates than Ho:YAG laser. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e925-e926 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ahmed Ghazi More articles by this author Mahmoud Khalil More articles by this author Changyong Feng More articles by this author Scott Quarrier More articles by this author Rajat Jain More articles by this author Expand All Advertisement Loading ...

Laser Transmission Welding is a promising joining technology technique – A Recent Review

Laser transmission welding (LTW) is one of the latest evolutions in joining technology. Simply, it involves joining two similar or dissimilar materials by melting and fusing two parts at their interface using laser radiation. The upper material is transparent in order to allow the laser radiation to pass and heat the second material which is in this case an absorbent material. This technique is also known with other names such as Laser Plastic Welding, Through-Transmission Welding and Laser Assisted Metal to Polymer Joining. The developments occurred in this field have also enabled LTW to approach different Lasers like Diode Laser, CO2 Laser, Nd: YAG Laser and Fiber Laser. This review aims to explain LTW process, working procedures, effect of Laser types and process parameters on this approach. It especially clarifies using LTW to weld thermoplastics materials together or with metals. It also attempts to help scholars to have an overview on LTW technique and achieve their answers related to this topic.

Comparison of Holmium:YAG and Thulium Fiber Lasers on the Risk of Laser Fiber Fracture.

Objectives: To compare the risk of laser fiber fracture between Ho:YAG laser and Thulium Fiber Laser (TFL) with different laser fiber diameters, laser settings, and fiber bending radii. METHODS: Lengths of 200, 272, and 365 μm single use fibers were used with a 30 W Ho:YAG laser and a 50 W Super Pulsed TFL. Laser fibers of 150 µm length were also tested with the TFL only. Five different increasingly smaller bend radii were tested: 1, 0.9, 0.75, 0.6, and 0.45 cm. A total of 13 different laser settings were tested for the Ho:YAG laser: six fragmentation settings with a short pulse duration, and seven dusting settings with a long pulse duration. A total of 33 different laser settings were tested for the TFL. Three laser settings were common two both lasers: 0.5 J × 12 Hz, 0.8 J × 8 Hz, 2 J × 3 Hz. The laser was activated for 5 min or until fiber fracture. Each measurement was performed ten times. Results: While fiber failures occurred with all fiber diameters with Ho:YAG laser, none were reported with TFL. Identified risk factors of fiber fracture with the Ho:YAG laser were short pulse and high energy for the 365 µm fibers (p = 0.041), but not for the 200 and 272 µm fibers (p = 1 and p = 0.43, respectively). High frequency was not a risk factor of fiber fracture. Fiber diameter also seemed to be a risk factor of fracture. The 200 µm fibers broke more frequently than the 272 and 365 µm ones (p = 0.039). There was a trend for a higher number of fractures with the 365 µm fibers compared to the 272 µm ones, these occurring at a larger bend radius, but this difference was not significant. Conclusion: TFL appears to be a safer laser regarding the risk of fiber fracture than Ho:YAG when used with fibers in a deflected position.

P0212 - An in vitro analysis of holmium: YAG and thulium fiber laser ablation rates

P0212 - An in vitro analysis of holmium: YAG and thulium fiber laser ablation rates

Basic and advanced technological evolution of laser lithotripsy over the past decade: An educational review by the European Society of Urotechnology Section of the European Association of Urology

Laser disintegration of urinary stones is a cornerstone of urolithiasis treatment in the modern era. Despite the wide clinical use of stone lasers, basic and advanced technological achievements and developments are difficult to comprehend and interpret by the average urologist. A descriptive analysis of laser production and stone disintegration mechanisms was performed. We focused on physics of modern types of lithotripters, the construction of laser fibers, laser parameters, new modes, settings, and lithotripsy techniques. The main principle of laser emission remains the same since the first emitting laser was produced. Peak power density and short interaction time lead to photothermal effects responsible for stone disintegration. Modern lithotripters such as Holmium: YAG (low/high power, Moses technology) and thulium fiber laser show basic construction differences with the physical properties of the latter being superior, at least in in vitro studies. By adjusting lasing parameters, a wide spectrum of stone ablation from fragmentation to dusting can be achieved. New technology allows for the production of real dust. Knowledge of laser fiber construction and physical properties are useful in marketing and clinical use. Urologists should understand the physical and physiological background of the lasers used in their everyday practice for stone fragmentation.

Basic and advanced technological evolution of laser lithotripsy over the past decade: An educational review by the European Society of Urotechnology Section of the European Association of Urology.

Laser disintegration of urinary stones is a cornerstone of urolithiasis treatment in the modern era. Despite the wide clinical use of stone lasers, basic and advanced technological achievements and developments are difficult to comprehend and interpret by the average urologist. A descriptive analysis of laser production and stone disintegration mechanisms was performed. We focused on physics of modern types of lithotripters, the construction of laser fibers, laser parameters, new modes, settings, and lithotripsy techniques. The main principle of laser emission remains the same since the first emitting laser was produced. Peak power density and short interaction time lead to photothermal effects responsible for stone disintegration. Modern lithotripters such as Holmium: YAG (low/high power, Moses technology) and thulium fiber laser show basic construction differences with the physical properties of the latter being superior, at least in in vitro studies. By adjusting lasing parameters, a wide spectrum of stone ablation from fragmentation to dusting can be achieved. New technology allows for the production of real dust. Knowledge of laser fiber construction and physical properties are useful in marketing and clinical use. Urologists should understand the physical and physiological background of the lasers used in their everyday practice for stone fragmentation.

Efficacy of an Er:YAG laser in the decontamination of dental implant surfaces: An in vitro study.

Emergence of peri-implant diseases led to the development of various methods for implant surface decontamination. This study was designed to compare the efficacy of biofilm removal from implant-like titanium surfaces by an erbium-doped yttrium-aluminum-garnet (Er:YAG) laser, titanium brush, and carbon fiber curet. Eight study subjects were recruited. A custom mouth appliance that held eight sandblasted and acid-etched titanium discs was fabricated for each subject. Subjects were asked to wear this appliance for 72hours to allow for biofilm development. After retrieval, discs were removed and randomized to one of four treatment groups. The discs were stained with a two-component nucleic acid dye kit, and the residual biofilm was visualized under fluorescence microscopy. Quantification of residual biofilm was performed using an image analysis software and expressed as the percentage surface area. Fifty-nine titanium discs were randomized to the four treatment groups. The percentage of titanium disc area covered by residual biofilm was 74.0% ± 21.6%, 32.8% ± 24.0%, 11.8% ± 10.3%, and 20.1% ± 19.2% in the control, Er:YAG, titanium brush and carbon fiber curet groups, respectively (mean ± SD). The biofilm-covered area significantly decreased in each of the three treatment groups compared with control (P< 0.008). Comparisons between treatment groups did not reveal statistical significance. Er:YAG laser treatment is an effective method for reducing the bacterial biofilm on titanium discs. However, on a threadless titanium surface, Er:YAG laser does not exhibit a significantly greater efficacy in biofilm removal than commonly used titanium brushes or carbon fiber curets.

Parametric Analysis of Laser Beam Percussion Drilling for Thin Titanium Alloy Sheet Using Yb: Yag Fiber Laser

Laser beam percussion drilling (LBPD) can create high density holes in aerospace materials with the repeated application of laser pulses at a single spot. In this study, one-parameter-at-a-time approach has been used to investigate the individual effect of peak power, pulse width and pulse frequency on geometrical accuracy and metallurgical distortion during LBPD of 0.85[Formula: see text]mm thick Ti–6Al–4V sheet using 200[Formula: see text]W Yb:YAG fiber laser. It has been found that the output parameters behave differently at the higher and lower values of a particular input process. The increase of pulse width from 1 to 1.50[Formula: see text]ms increases hole taper by 20% whereas the same corresponding change from 1.50 to 2.00[Formula: see text]ms reduces the taper by 20%. The increase of pulse frequency from 10 to 50[Formula: see text]Hz reduces hole circularity by 40% but the same proportionate change from 50 to 90[Formula: see text]Hz reduces circularity by 79%. Increase of peak power from 1.70 to 2.0[Formula: see text]kW increases hole taper by 8% but the corresponding increase from 2 to 2.30[Formula: see text]kW is 143%.

The Effect of Laser Beam Processing on the Properties of WC-Co Coatings Deposited on Steel.

The main objective of the present work is to determine the effects of laser processing on properties of WC-Co electro-spark deposited (ESD) coatings on steel substrates. Tungsten carbide coatings have been applied to steel substrates using a manual electrode feeder, model EIL-8A. The laser beam processing (LBP) of electro-spark coatings was performed using an Nd:YAG fiber laser. The microstructure and properties of laser treated/melted coatings were evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), surface geometric structure (SGS) and roughness measurements and adhesion, microhardness, residual stresses, corrosion resistance and application tests. The obtained experimental data were subjected to statistical analysis and multidimensional numerical and visual exploratory techniques. It has been shown conclusively that the laser-treated ESD WC-Co coatings are characterized by lower microhardness, higher resistance to corrosion, increased roughness and better adhesion to the substrate. LBP homogenizes the chemical composition, refines the microstructure and heals microcracks and pores of ESD coatings. The laser treated ESD WC-Co coatings can be used in frictional sliding nodes (e.g., on the front seal rings used in pumps) and as protective layers.

Studies on surface morphology of under liquid laser ablated magnesium alloy

The magnesium-based alloys have limited wear resistance and tribological properties and tend to lose their functionality prematurely under sliding conditions. This can be addressed through conventional surface treatment and coatings. The surface texturing and coating can be simultaneously achieved by carrying out laser ablation under liquid medium. This improves the lubricant film, the unwanted thermal cracking, vaporization of metal and metallurgical changes. In this experimental investigation, the disintegrated melt deposition (DMD) processed Mg3Al alloy was subjected to under liquid laser ablation in 1 proponal containing graphite particles of size range 5–9 μm stirred at 1900 rpm by a magnetic stirrer. The under liquid laser ablation yielded nanostructured surface with grooves and islands that promote wettability and the presence of graphite ensuring an improvement of tribological properties. In this study, a 60 W power Nd YAG fiber laser was used to etch the surface and achieve the under liquid ablation. The surface roughness and morphology were studied using Atomic Force Microscopy and the chemical analysis of the laser-treated surface was done using Raman spectroscopy.