F. Arias-González

Processing of pure Ti by rapid prototyping based on laser cladding

Rapid prototyping based on laser cladding is an additive manufacturing (AM) process based on the overlapping of cladding tracks to produce functional components. Powder or wire are fed into a melting pool created using laser radiation as a heat source and the relative movement between the beam and the work piece makes possible to generate pieces layer-by-layer. This technique can be applied for any material which can be melted and the components can be manufactured directly according to a computer aided design (CAD) model. Additive manufacturing is particularly interesting to produce titanium components because, in this case, the loss of material produced by subtractive manufacturing methods is highly costly. Moreover, titanium and its alloys are widely used in biomedical, aircraft, chemical and marine industries due to their biocompatibility, excellent corrosion resistance and superior strength-to-weight ratio. In this research work, a near-infrared laser delivering a maximum power of 500W is used to produce pure titanium thin parts. Dimensions and surface morphology are characterized using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), the hardness by nanoindentation and the composition by X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDS). The aim of this work is to establish the conditions under which satisfactory properties are obtained and to understand the relationship between microstructure/properties and deposition parameters.

Laser bioengineering of glass-titanium implants surface

Osseointegration is the mean challenge when surgical treatments fight against load-bearing bone diseases. Absolute bone replacement by a synthetic implant has to be completed not only from the mechanics point of view, but also from a biological approach. Suitable strength, resilience and stress distribution of titanium alloy implants are spoiled by the lack of optimal biological characteristics. The inert quality of extra low interstitial titanium alloy, which make it the most attractive metallic alloy for biomedical applications, oppose to an ideal surface with bone cell affinity, and capable to stimulate bone attachment bone growth. Diverse laser treatments have been proven as effective tools to modify surface properties, such as wettability in contact to physiological fluids, or osteoblast guided and slightly enhanced attachment. The laser surface cladding can go beyond by providing titanium alloy surfaces with osteoconduction and osteoinduction properties. In this research work, the laser radiation is used to produce bioactive glass coatings on Ti6Al4V alloy substrates. Specific silicate bioactive glass compositions has been investigated to achieve suitable surface tension and viscosity temperature behavior during processing, and to provide with the required release of bone growth gene up regulation agents in the course of resorption mediated by physiological fluids. The produced coatings and interfaces, the surface osteoconduction properties, and the chemical species release in simulated physiological fluid were characterized by scanning electron microscopy (SEM), hot stage microscopy (HSM), X-ray diffraction (XRD), X ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR).

Microstructure and crystallographic texture of pure titanium parts generated by laser additive manufacturing

In this paper, the microstructure and crystallographic texture of pure Ti thin walls generated by Additive Manufacturing based on Laser Cladding (AMLC) are analyzed in depth. From the results obtained, it is possible to better understand the AMLC process of pure titanium. The microstructure observed in the samples consists of large elongated columnar prior β grains which have grown epitaxially from the substrate to the top, in parallel to the building direction. Within the prior β grains, α-Ti lamellae and lamellar colonies are the result of cooling from above the β-transus temperature. This transformation follows the Burgers relationship and the result is a basket-weave microstructure with a strong crystallographic texture. Finally, a thermal treatment is proposed to transform the microstructure of the as-deposited samples into an equiaxed microstructure of α-Ti grains.

Optimization of laser drilling of slate tiles

Slate is a natural rock with good mechanical properties and nice aesthetic appearance. Its utilization in residential constructions confers an elegant rustic external appearance, while keeping an excellent impermeability and robustness. Therefore, this rock is widely used in building construction, decoration, fireplaces and even handcrafted objects, particularly in regions owning natural slate quarries.The modern building construction is nowadays asking for improved manufacturing processes for its roofing materials since market requirements are continuously increasing. However, there is currently a lack of a reliable drilling process for slate. Making drills on a slate tile is still a difficult task because of its high hardness and its particular structure with parallel layers. A significant number of slate tiles are broken due to mechanical stress caused by traditional drilling tools. In this sense, lasers have already been demonstrated as a reliable tool for generate holes on a wide variety of materials and, particularly, in some stones. Due to its high precision, energy density, and its availability to be automated a great number of small holes can be produce in a short period of time.In this work, an experimental analysis on the CO2 laser drilling process of slate tiles is presented. We have used a systematic approach to determine the most adequate processing conditions to produce submillimeter holes in 5 mm thick slate tiles with good quality as well as in a minimum processing time.Slate is a natural rock with good mechanical properties and nice aesthetic appearance. Its utilization in residential constructions confers an elegant rustic external appearance, while keeping an excellent impermeability and robustness. Therefore, this rock is widely used in building construction, decoration, fireplaces and even handcrafted objects, particularly in regions owning natural slate quarries.The modern building construction is nowadays asking for improved manufacturing processes for its roofing materials since market requirements are continuously increasing. However, there is currently a lack of a reliable drilling process for slate. Making drills on a slate tile is still a difficult task because of its high hardness and its particular structure with parallel layers. A significant number of slate tiles are broken due to mechanical stress caused by traditional drilling tools. In this sense, lasers have already been demonstrated as a reliable tool for generate holes on a wide variety of materials...

Sub-milimetric titanium parts generated by rapid prototyping based on laser cladding

Rapid Prototyping based on Laser Cladding is an Additive Manufacturing (AM) technique that can be applied to any material which can be melted. It can be found under different names and acronyms: Direct Laser Deposition (DLD), Laser Metal Deposition (LMD), Laser Engineering Net Shaping (LENS), etc. Despite the different names, the basics of these methods are the same: a scanning laser beam creates a molten pool, in which a precursor material is fed; by the relative movement between the substrate and the laser, a cladding track is generated; and by the overlapping of cladding tracks is possible to manufacture functional 3D parts, layer by layer. Apart from that, titanium and its alloys present excellent properties like corrosion resistance, biocompatibility and high strength-to-weight ratio. They are widely used by several industries, in particular for biomedical, chemical, aircraft and marine applications. However, the machinability of titanium is considered poor and the loss of material produced by conventional manufacturing methods is highly costly. Rapid Prototyping Based on Laser Cladding is a solution to manufacture functional parts of titanium and avoid these obstacles. In this research work, Rapid Prototyping based on Laser Cladding is applied to obtain sub-milimetric simple titanium parts. A fiber laser delivering a maximum power of 200 W is used to process the precursor material selected: commercial pure titanium (cp-Ti) powder. The parts generated are analyzed by different characterization methods to study the microstructure, composition and properties.Rapid Prototyping based on Laser Cladding is an Additive Manufacturing (AM) technique that can be applied to any material which can be melted. It can be found under different names and acronyms: Direct Laser Deposition (DLD), Laser Metal Deposition (LMD), Laser Engineering Net Shaping (LENS), etc. Despite the different names, the basics of these methods are the same: a scanning laser beam creates a molten pool, in which a precursor material is fed; by the relative movement between the substrate and the laser, a cladding track is generated; and by the overlapping of cladding tracks is possible to manufacture functional 3D parts, layer by layer. Apart from that, titanium and its alloys present excellent properties like corrosion resistance, biocompatibility and high strength-to-weight ratio. They are widely used by several industries, in particular for biomedical, chemical, aircraft and marine applications. However, the machinability of titanium is considered poor and the loss of material produced by conven...

Rapid prototyping of metallic structures based on laser micro-cladding

In the last years, the demand of products fabricated by rapid prototyping techniques has grown sharply for many different uses, such as the fabrication of scale models and functional pieces with special characteristics for the industrial sector or the production of implants in the biomedical sector. This fact is joined to the research effort which is being carried out to obtain micro-scale products like biomedical sensors, a huge amount of MEMS devices or even 3D batteries in order to overcome some of the limits of the current macro-devices.In the majority of the cases, thin film techniques like sputtering or LCVD as well as techniques based on 3D printing are being used to obtain the micro-scale devices, with the limitations inherent to these techniques like the need of vacuum systems, the processing speed or the restrictions in the types of materials. In that sense, some of these limitations could be overcome adopting a raping prototyping technique based on laser cladding. In this work we propose the rapid prototyping of functional parts based on laser micro-cladding, which can be considered as a downscaling of conventional laser cladding, due to its higher processing rate and its ability to work with a wide range of materials. On the other hand, another main feature of this one step additive technique is the low thermal loads applied to the substrate, which is an important parameter in applications where the laser interaction zone is close to sensitive elements.An experimental set-up based on the use of a single mode fiber laser and a lateral powder injection system adequate to supply micron and submicron particles was used to produce metallic 3D structures in the micrometer range. The influence of several processing parameters on the geometry and mechanical properties of the tridimensional structures were systematically studied.In the last years, the demand of products fabricated by rapid prototyping techniques has grown sharply for many different uses, such as the fabrication of scale models and functional pieces with special characteristics for the industrial sector or the production of implants in the biomedical sector. This fact is joined to the research effort which is being carried out to obtain micro-scale products like biomedical sensors, a huge amount of MEMS devices or even 3D batteries in order to overcome some of the limits of the current macro-devices.In the majority of the cases, thin film techniques like sputtering or LCVD as well as techniques based on 3D printing are being used to obtain the micro-scale devices, with the limitations inherent to these techniques like the need of vacuum systems, the processing speed or the restrictions in the types of materials. In that sense, some of these limitations could be overcome adopting a raping prototyping technique based on laser cladding. In this work we propose the ra...

Marine resources and sub-products valorisation for medical applications by laser assisted techniques

In order to preserve the marine natural environment the European extractive regulations for fishing and canning industries were remarkably tightened during last years. The reduction of discard production was enforced, in addition to the compulsory sub product unloading at seaport, raised the fishing sub-products availability on dry land. Moreover, the extra costs of preserving regulations increased the interest of fishing and canning companies on the development of new processes to add value to these sub products. Therefore, the research activity of several groups along the European Atlantic coast was directed towards the study of the potential of both marine precursor materials and valorization procedures.In this work, we compare the results of several strategies to transform marine resources and fishing sub-products into materials for biomedical applications. These methods involve the direct and indirect treatment of fish bones and seafood shells by laser assisted techniques, such as laser ablation or laser cladding. Thus, bioceramic materials and implant coatings for bone restoration and other biomedical purposes can be produced from marine precursor materials. This work explores in detail the feasibility to produce marine origin bioactive glass coatings onto Ti6Al4V alloy substrates by means of the laser cladding technique. The produced coatings and interfaces and the chemical species released in simulated physiological fluids were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF).In order to preserve the marine natural environment the European extractive regulations for fishing and canning industries were remarkably tightened during last years. The reduction of discard production was enforced, in addition to the compulsory sub product unloading at seaport, raised the fishing sub-products availability on dry land. Moreover, the extra costs of preserving regulations increased the interest of fishing and canning companies on the development of new processes to add value to these sub products. Therefore, the research activity of several groups along the European Atlantic coast was directed towards the study of the potential of both marine precursor materials and valorization procedures.In this work, we compare the results of several strategies to transform marine resources and fishing sub-products into materials for biomedical applications. These methods involve the direct and indirect treatment of fish bones and seafood shells by laser assisted techniques, such as laser ablation or l...

Laser processing of phenolic wood substitutes

Phenolic resin boards (PRB) are wood substitutes that comprises of a thick core exclusively made of phenolic resin covered by a thin sheet of melamine resin imitating the aspect of natural wood. The use of these materials in furniture and in construction industry has proliferated during last years. Boards made of phenolic resins are dense, hard and very difficult to cut using band saws, disc saws, or milling cutters. Nevertheless, these difficulties can be overcome by means of laser cutting, which is one of the most firmly established techniques for separating materials. This is due to the great advantages of this technique over traditional cutting methods, such as its versatility and flexibility that allow effective cutting. Nevertheless, charring of the cut edge surface caused by laser induced thermal degradation degrades the cut quality under non-optimized processing conditions. In this research work the viability and quality of CO2 laser cutting process of phenolic resin boards and wood particleboard panels has been evaluated. The present work validates the cut of phenolic resin boards by CO2 lasers using a high laser power and elevated cutting speeds. Moreover, this process involves a serious health hazard since the combustion and decomposition of wood may produce fumes and vapors, which can be toxic and carcinogenic according to the International Chemical Safety Cards (ICSC). Therefore, this work was complemented by the assessment of the potential toxicity of the condensed residues formed on the cut edges, and assessment of the chemistry of the generated fumes by chromatography.