Laser Surface Treatment Research Articles

Laser surface treatment of pure titanium: Microstructural analysis, wear properties, and corrosion behavior of titanium carbide coatings in Hank's physiological solution

Titanium exhibits poor mechanical features such as low hardness and wear resistance. In this research, we considerably enhance the hardness and wear resistance of Ti by a simple laser surface treatment method. Titanium carbide (TiC) structure was successfully generated on Ti samples by means of laser. Vickers hardness indenter, wear test, impedance spectroscopy, and polarization analyses were carried out to scrutinize the mechanical and corrosion properties of samples. Adhesion between Ti and the formed TiC structure is favorite aspect of this method. The results confirmed that the TiC layer improved the mechanical hardness of the Ti. Additionally, the friction coefficient values of laser-treated Ti samples dramatically decreased. The surface roughness of laser-treated Ti declined to its minimum value with increase in laser-treatment time. Although, laser-surface treatment of Ti did not make an evident change in the corrosion resistance of Ti in Hank's physiological solution compared to reference Ti, the escalation of Ti hardness with laser-treatment time is a favorable aspect of this method.

Short thermal cycle treatment with laser of vanadium microalloyed steels

Abstract Improvement of crankshaft fatigue properties can be approached by altering its mechanical properties in the surface, such as laser surface treatment. Laser beam treatment offers efficient and precise surface hardening processing with possibility of reducing the production cost compared to the conventional hardening techniques. However, its characteristic of having short thermal cycle can be a challenge for the development of laser surface hardening techniques, such as inadequacy of literatures in phase transformation and resulting mechanical properties under rapid heating and cooling rate. Therefore, this work investigated the impact of short thermal cycles induced by the laser beam on the resulting microstructure and hardness properties in the surface of 38MnSiVS5 and 44MnSiVS6 microalloyed steels. Temperature cycles during the process were recorded and examined with the resulting microstructure along with microhardness values. 44MnSiVS6 microalloyed steel, which contains ca. double the amount of vanadium compared to 38MnSiVS5 steel, produces finer ferrite grains in the treated area for all investigated short thermal cycles. This fine-grained microstructure leads to steady hardness distributions in the treated area. The short thermal cycle was assumed to be unable to dissolve the vanadium precipitates that reside in the ferrite grains, which then initiate precipitation hardening.

Surface Properties Enhancement of Light Alloys by Appliance of Laser Treatment

Laser surface treatment is at present one of up-to-date methods for surface layer engineering, in this technique into the matrix material are introduced some amount of alloying additives. So the surface layer is obtained in form of composite material consisting of ceramic particle powders with different properties influencing the surface layer appliance possibilities. Using the technology it is possible to obtain a layer revealing a structured structure consisting of the heat affected zone (HAZ), transition zone (TZ) and remelted zone (RZ), as well as the substrate material. The laser is without cracks and defects as well as has with a slightly higher hardness value compared to the raw substrate material. The used laser power range is set in the range between 1.0 to 2.5 Kw, with the laser scan rate of the beam head in a range between 0.25-0.75 m/min, depending of the applied laser power and material used for alloying.This study was conducted to determine the effect of carbide on oxide ceramic powders addition on the microstructure and mechanical properties their changes and enhancement possibilities during a rapid solidification process of the remelted surface layer. The investigation should help to use this laser treatment technology for alloying of ceramic powder particles into the surface of light alloys, especially magnesium and aluminium. The scientific reason of this work is the usage of High Power Diode Laser (HPDL) for improvement of aluminium`s mechanical properties, especially the surface hardness and war resistance.There was found during the investigations and analysis of the results that, the obtained surface layer is without cracks and defects as well as with a relatively higher hardness compared to the raw material, after standard heat treatment. The hardness value increases according to the laser power used so that the highest power applied gives the highest hardness value in the remelted layer, similar relation can be found in the wear resistance parameters, which increases also with increasing laser power.The findings of the investigations allows to state, that the distribution of the used ceramic particles is generally satisfied, especially the carbide powder was confirmed in the alloys matrix, the particles are mainly present in the upper part of the surface layer or in the bottom zone of the remelted area. The hardness value increases in general according to the laser power used and the highest power results with the highest hardness value in the surface layer. The main aim of this work is to investigate and determine the effect of HPDL remelting and alloying on the cast Al-Si-Cu and Mg-Al-Cu cast aluminium and cast magnesium alloys micro structure for possible application in real working conditions mainly for light metal constructions as well as in many branches of the industry like automotive and rail transportation.

Laser Desorption of Organic Compound Ions from a Silicon Surface Modified by Laser Irradiation

Laser desorption of organic compound ions from specially prepared surfaces is known as surface-assisted laser desorption/ionization (SALDI). In this work the properties of a SALDI ion emitter obtained by two-stage laser treatment of crystalline silicon surface have been investigated. The laser surface treatment leads to the formation of a layer with nanoscale objects—quantum dots (QDs) less than 10 nm in size, providing laser desorption of organic compound ions. A change in the desorbing laser wavelength from 351 to 263 nm at comparable laser-exposed spot sizes and fluences results in a sharp decrease in the formation efficiency for MH+ ions and appearance of ions M+ for the same analytes. The effect is apparently determined by the spectral properties of the quantum dots formed on the silicon surface under laser irradiation.

Tribological Characteristic of Tool Steel Surface Layer Alloyed Using Laser

The article presents the results of research on the impact of laser surface treatment on selected steel properties. The laser treatment consisted of remelting and alloying high speed steel using hard ceramic phase powders. A high-power diode laser was used in the experiment to examine the effect of parameters such as beam power and powder type on the structure and properties of the surface layer. A structural mechanism was observed consisting in obtaining, after laser processing, a super fine crystalline structure and a dendritic structure at the remelting zone. Structural changes have been found to be associated with improved properties such as hardness, microhardness and wear resistance. Steel treated with conventional heat treatment was used as a comparative material.

Дослідження вольт-амперних характеристик дротяної електронної гармати Пірса для електронно-променевої мікрообробки діелектриків

The main energy characteristics of Pierce wire electron beam gun, which is used for treatment of dielectric materials in vacuum, are considered. The modes of operation of such a gun depending on their energy characteristics are studied. It is established that at a fixed width of the anode gap of 2.0 mm it is possible to implement the main technological modes of low-energy EBT dielectrics (including optical glass). The results of electron beam treatment of dielectrics with the results of their laser surface treatment are compared. The reduction of residual surface microroughnesses for optical glass K8 up to 26 times with EBT and up to 14 times with surface laser treatment was established. It is shown that the electron beam treatment of the tape shape, in contrast to the surface laser treatment, allows to completely eliminate the waviness of the optical surface. On the example of plates made of optical glass K8 it is proved that electron beam treatment of surfaces of dielectric materials allows to increase the reproducibility of the results of such micromachining by purity and residual nanorelief by 18 ... 25 %.

331 レーザーによる建築材料の表面処理研究 : その3. 稲田御影石の粗面化

331 レーザーによる建築材料の表面処理研究 : その3. 稲田御影石の粗面化

Effect of different laser energy densities on the corrosion resistance of aluminum alloys

Purpose Laser cleaning, as a new type of cleaning technology, has the advantages of environment-friendliness, better selectivity, better controllability and higher efficiency compared to traditional chemical cleaning or grinding. This paper aims to use ultra-fast surface laser cleaning equipment built in laboratory to study the influence of different energy density (7.6, 11.5 and 15.3 J/cm2) on corrosion resistance of the aluminum alloy A7N01P-T4, a high-speed train body material. Design/methodology/approach SEM, white light interferometer, EDS and XPS were used to analyze the surface morphology, roughness, element content and oxide layer composition of aluminum alloy before and after cleaning. The corrosion resistance was studied by electrochemical experiments and exfoliation corrosion experiments. Findings The results showed that new oxide scale was formed on the surface after laser cleaning. The changes of surface roughness and chemical composition of oxide scale made a significant influence on corrosion behaviors. Better corrosion resistance was obtained with the energy density increased, and at the energy density of 11.5 J/cm2, aluminum alloy exhibited the best corrosion resistance. Research limitations/implications The paper only studies specific aluminum alloys and is not universal. Laser cleaning equipment is set up for the laboratory and has not yet been put into industrial production. Practical implications This paper indicated that ultra-fast laser processing was a new direction for the development of industrial equipment surface cleaning and carried out ultra-fast laser of aluminum alloy surface cleaning had certain research significance for its corrosion resistance. Social implications Compared with the conventional cleaning methods such as air abrasives grinding or chemical cleaning, laser cleaning has advantages of environment-friendliness, better selectivity, better controllability and higher efficiency. Laser cleaning can not only protect the environment, but also improve cleaning efficiency. Originality/value Changes in the surface of aluminum alloys after ultra-fast surface laser treatment were found, and the mechanism of changes in aluminum alloy corrosion properties was clarified.

Laser Surface Hardening of Ni-hard White Cast Iron

Laser surface treatment on two different types of nickel–chromium white cast iron (Ni-hard) alloys (Ni-hard 1 and Ni-hard 4) was investigated. Nd:YAG laser of 2.2-kw with continuous wave was used. Ni-hard alloys are promising engineering materials, which are extensively used in applications where good resistance to abrasion wear is essential. The conventional hardening of such alloys leads to high wear resistance nevertheless, the core of the alloy suffers from low toughness. Therefore, it would be beneficial to harden the surface via laser surface technology which keeps the core tough enough to resist high impact shocks. A laser power of different levels (600, 800 and 1000 Watts) corresponding to three different laser scanning speeds (3, 4 and 5 m·min−1) was adopted hoping to reach optimum conditions for wear resistance and impact toughness. The optimum condition for both properties was recorded at heat input of 16.78 J·mm−2. The present findings reflect that the microhardness values and wear resistance clearly increased after laser hardening by almost three times due to laser surface hardening, whereas, the impact toughness was increased from five joules obtained from conventionally heat-treated samples to 6.4 J as gained from laser-treated samples.

Effect of laser surface treatments on a thermoplastic PA 6/carbon composite to enhance the bonding strength

Adhesive bonding is an appropriate method to assemble structural composite components without a machining process. Compared with the properties of the carbon fiber reinforced thermoset polymer (CFRP), the carbon fiber reinforced thermoplastic polymer (CFRTP) have advantages, such as recyclability and superb impact, corrosion and temperature resistance. However, CFRTP have a low bonding strength with structural adhesives. In this study, a laser treatment was applied to an epoxy based CFRP and polyamide 6 (PA 6) based CFRTP surfaces to improve the adhesive bonding strength. Shear and tensile adhesive bonding tests were performed, and the mechanism of the laser treatment was investigated by the failure mode, surface free energy and Fourier transform infrared spectroscopy (FTIR) analyses. The adhesive bonding strengths of the CFRP and CFRTP were significantly improved by the laser treatment, and each wettability and functional groups is increased.

Analysis of Enhanced Pool Boiling Heat Transfer on Laser—Textured Surfaces

Enhancement of pool boiling heat transfer can be attained with a number of passive and active techniques. The paper experimentally analyses the impact of laser treatment of the copper surfaces on pool boiling heat transfer of distilled water and ethyl alcohol. The samples were modified with a laser beam to produce longitudinal grooves of highly developed microstructures in the laser textured area. Specimens of different groove depths, groove widths and micro-fin widths were produced. The results indicate a significant influence of laser processing on heat flux dissipated from the surfaces and heat transfer enhancement for all the samples tested. The experimental results have been generalized in the form of a heat flux correlation based on a modified model of enhanced pool boiling heat transfer.

Corrosion resistance enhancement by laser and reduced graphene oxide-based nano-silver for 1050 aluminum alloy

This paper describes a new approach for enhancing the pitting corrosion resistance of aluminum 1050 alloy. The aluminum surface was treated by pulsed laser (850 mJ) prior to anodization. Anodization was carried out at 15 V in a hybrid electrolyte saturated with reduced graphene nanocomposite (rGO-Ag). The oxide layer was analyzed using polarization and cyclic voltammetry tests. The microstructure and metal composition of the modified surface structure were investigated using a scanning electron microscope and an energy-dispersive detector. The addition of graphene nanocomposite to the electrolyte can enhance the current density (Icorr) to 96.60 µA/cm2 and corrosion potential (Ecorr) to −395.4 mV. Q-switched Nd:YAG pulsed laser surface treatment offered a substantially increase in the corrosion resistance. Laser performance results indicated a substantial difference in the protection of aluminum surface compared with that of the untreated sample. The process employed in this research aimed at improving the pitting corrosion resistance and enhancing the chemical reaction resistance of the aluminum oxide layer in artificial seawater environment.

Er,Cr:YSGG laser surface treatment of gamma titanium aluminide: Scanning electron microscopy-energy-dispersive X-ray spectrometer analysis, wettability and Eikenella corrodens and Aggregatibacter actinomycetemcomitans bacteria count-in vitro study.

Dental implants play an important role in oral health. Titanium dental implants must endure the complex microflora environment of the oral cavity. Moreover, bacterial infections have been considered as one of the most important factors of implant failure. The issue of dental improvement through modification of chemical composition and surface treatment has received considerable critical attention. γ-TiAl as a novo biocompatible material revealed a slower corrosion rate in biological media rather Ti-6Al-4V. The objective of this study is to investigate the effect of Er,Cr:YSGG laser on γ-TiAl in comparison with sandblasted and acid-etched samples as the control groups and machined samples.Wettability, surface roughness, surface topography, scanning electron microscopy-energy dispersive X-ray spectrometer analysis of surface and subsurface of samples were investigated and bacteria counts of two periodontal bacterial strains (Aggregatibacter actinomycetemcomitans and Eikenella corrodens) were evaluated on the Er,Cr:YSGG laser surface-treated sandblasted and acid-etched and machined samples.The results of this investigation show that Er,Cr:YSGG laser surface treatment affects surface roughness, surface topography, wettability, chemical composition of the surface and bacteria count. Scanning electron microscopy-energy dispersive X-ray spectrometer analysis of the sample revealed the increment of titanium and oxygen content and reduction of aluminum content in the surface and subsurface layer. A. actinomycetemcomitans and E. corrodens count were found from the lowest level to highest in the sandblasted and acid-etched samples, laser samples and machined samples, respectively.Using controlled parameters of Er,Cr:YSGG laser ensured no significant adverse alteration. The findings to emerge from this study revealed the significant correlation between microbial count and wettability. Furthermore, the contact angle strongly correlated with surface roughness.

The Laser Surface Treatment Effective on Structural Properties for Invar Alloy (Fe-Ni) Type Prepared by Powder Technology

This research aimed to prepare (Fe-Ni) alloy by powder technology method for its technological and commercial importance. Iron and Nickel powders were tacking then their powders mixed and blended together with percent (63% Fe-37% Ni), then the powders compacted isostatic cold pressure at (6 ton). Laser surface treatment was done for the samples with different energies (0, 200, 260, 300) mJ and pulse time (10 sec) At a distance (100 cm). The X-ray diffractions test indicated that all samples have Face Center Cubic (F.C.C), and the samples at 300 mJ has best properties which include increase of phases intensity and decrease of grain size according to Debye-Scherrer equation. The Atomic Force Microscope (AFM) also shows better properties with increase laser energy. Where increased soft-ness of surface, homogeneity surface and decrease in grain size with increase laser energy. The laser analysis resulted that melting all surface molecules which led to improvement in the structural properties.

Effects of niobium (Nb) on mechanical properties of laser coated Nitinol (NiTi) used for surface modification of Ti6A14V alloy

Abstract:Laser surface treatment is widely used as an engineering technique due to its special characteristics and several advantages over other surface modification techniques. In the present study, elemental mechanically pre-alloyed powder consisting of Niobium, Titanium and Nickel was deposited onto a grade 5 Titanium alloy substrates to form a high wear resistance coating. This was such that the surface mechanical properties of the base metal can be improved. The fabricated samples were characterised using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), Differential Scanning Calorimeter (DSC), micro hardness tester and wear machine. The deposited coatings were well bonded and consisted of various phases. Hardness was seen decrease with increase in Nb content while wear resistance increasing with increase in niobium content.

Experimental and numerical characterization of titanium-based fibre metal laminates

The effect of applying a laser surface treatment to the metal plies in a fibre metal laminate (FML) based on a titanium alloy and a fibre reinforced composite has been evaluated and the response compared to that measured on a comparable untreated laminate. It has been shown that applying a laser fluence of 4.54 J/cm2 to the titanium layers in the FML results in a good bond strength between the titanium foil and the glass fibre/PEKK composite. The response of the FMLs under dynamic loading was studied and compared with that measured at quasi-static rates. It has been shown that FMLs based on a titanium alloy exhibit a rate-sensitivity, both in terms of energy absorption and the maximum impact force. An examination of cross-sections removed from samples following testing at dynamic and quasi-static loading rates indicated that the FMLs absorbed energy through plastic deformation, tearing of the metal layers, delamination and fibre fracture. Finite element models were then developed to simulate the response of the FMLs under impact loading. The simulated results were validated against the corresponding experimental data by comparing both the load–displacement traces as well as the resulting failure modes, with good agreement being observed in most cases.

Effect of long-term mechanical cycling and laser surface treatment on piezoresistive properties of SEBS-CNTs composites

The piezoresistive behaviour of SEBS-CNTs nanocomposites was investigated to evaluate their.potential applications as strain sensors. Composites containing from 3%wt. to 7%wt. of CNTs were processed by injection moulding in order to evaluate the percolation threshold. The piezoresistive response under flexural strain of nanocomposites with a CNTs content above the percolation threshold was then studied. The nanocomposites showing the most promising performance were tested under cyclic conditions. Conductive tracks were then processed on nanocomposites surfaces (with 3 and 4% of CNTs) by means of a laser treatment. Samples with optimized laser tracks were then submitted to 1000 stretching/releasing cycles, showing improved piezoresistive performance.

Mechanism of TiC formation in laser surface treatment of the commercial pure titanium pre-coated by carbon using PVD process

The physical evaporation deposition (PVD) and titanium (CP–Ti) plate. The influence of area scanning speed on the structure of coating were studied by changing the laser working distances and Nd:YAG laser traveling speeds. Scanning electron microscopy (SEM) and also field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) were utilized to investigate the samples. The structure of produced coating mainly was affected by area scanning speed. At area scanning speeds lower than 7.5 mm2/s, one layer low TiC composite was produced due to the formation of deep melt pool with long melting time. One layer high TiC composite formed at area scanning speeds higher than 20 mm2/s as a result of shallow melt pool. Between theses values, two layers coating consisting of high and low TiC composite was obtained because the melt pool was relatively large and the required melting time for homogenization was not provided. The micro-hardness measurements showed that, the highest hardness (up to 6 times higher than the substrate) was obtained when two layers coating were synthesized. The dry sliding wear test demonstrated 62–93% reduction in the mass losses and wear rates in the two layers coatings. The average friction coefficient of the two layers coating reduced about 77%.

Modification of surface layers of metal parts by pulse laser processing

One of the common technological schemes for the laser processing of metal parts is laser «glazing» of the deposited thin layer of powder on the substrate, which makes it possible to obtain microcrystalline and amorphous structures in thin surface layers of parts. Pulse melting of small volumes of metal on the surface provides homogeneous liquids (melts), which, after crystallization, can fix the structure of a liquid with unique properties.The presence of three energy input ranges for pulsed laser surface treatment (ILPO) has been established. At an average level of energy input, a process of laser surfacing of the material occurs, while a high adhesive bond between the coating and the workpiece is fixed. The deposition of an amorphized iron-based alloy coating on a metal base of St3, 45 20X13 steels begins at a laser radiation density on the treatment surface of 1800–2000 W/mm2, and alloying at 3500–4000 W/mm2. With ILPO, the laser exposure zone (ZLV) has a layered structure – the fusion zone (ZO), the heat-affected zone (HAZ), and the source material zone. To obtain an amorphous-crystalline structure of the coating, the laser pulse frequency should not exceed 3–8 Hz.

Improving mode II fracture toughness of secondary bonded joints using laser patterning of adherends

We improve mode II fracture toughness of secondary bonded joints based on the laser treatment of adherend surfaces. We applied CO2 Laser treatment to adherend surface alternatively with low and high energy, resulting in a repeated pattern of rough and smooth surfaces. We used ENF test to characterize mode II fracture toughness, GII, of the bonded CFRP substrates. The results demonstrated that our proposed pattern arrested the crack propagation and triggered new damage mechanisms, such as adhesive cracking, adhesive failure and crack migration to the other interface. These additional mechanisms, some of them were non-local in nature, resulted in higher energy dissipation during propagation and, improved GII compared to joints with uniformly-treated adherends. The improvement in GII was dependent on the pattern morphology and reached up to 60%. The proposed strategy worked well for both thin and thick adhesives, and thus could be applied in aerospace and civil structures.