André Luiz Jardini Munhoz

Surface Finishes for Ti-6Al-4V Alloy Produced by Direct Metal Laser Sintering

The implant’s surface is responsible for direct interaction with the human body. For cases where osseointegration must be favored and the risk of bacteria proliferation is lower, rough surfaces are more suitable, while for implants where the risks are higher, a reduced surface roughness is required. This study aimed to analyze and produce different surface finishes on samples of Ti-6Al-4V alloy produced by additive manufacturing technique of Direct Metal Laser Sintering (DMLS). Surfaces of the samples were analyzed in the as-built condition, after blasting, after chemical etching, after electropolishing and two different combinations of these methods. The surfaces were studied using the technique of scanning electron microscopy, and surface roughness and mass measurements. The lower roughness value was obtained after a combination of blasting and chemical etching. Blasting results in a surface with uniform roughness while chemical etching cleans the surface and reduces its roughness.

Paired evaluation of calvarial reconstruction with prototyped titanium implants with and without ceramic coating

PURPOSE To investigate the osseointegration properties of prototyped implants with tridimensionally interconnected pores made of the Ti6Al4V alloy and the influence of a thin calcium phosphate coating. METHODS Bilateral critical size calvarial defects were created in thirty Wistar rats and filled with coated and uncoated implants in a randomized fashion. The animals were kept for 15, 45 and 90 days. Implant mechanical integration was evaluated with a push-out test. Bone-implant interface was analyzed using scanning electron microscopy. RESULTS The maximum force to produce initial displacement of the implants increased during the study period, reaching values around 100N for both types of implants. Intimate contact between bone and implant was present, with progressive bone growth into the pores. No significant differences were seen between coated and uncoated implants. CONCLUSION Adequate osseointegration can be achieved in calvarial reconstructions using prototyped Ti6Al4V Implants with the described characteristics of surface and porosity.

New infrared stereolithography: control of the parameters of the localized curing thermosensitive materials

In normal practice, stereolithography has been used for photosensitive resins where ultraviolet light (HeCd laser λ=O.352μm) initiates the curing process for prototypes construction. In this work we developed a new aspect of stereolithography, using CO2 laser (λ=1O.6μm) in thermosensitive materials where no shrinkage and post-cure treatment was observed. The bulk curing process in resins, epoxy unlike, has been proved useful in a new tethnique for fabrication of prototypes. Control of the laser parameters appears as an important tool for localized cure in the material. Our resin basic sample is composed by the thermosensitive epoxy resin proved to be (in weight) 10 parts, 1,4 parts diethilene triamine (the curing agent) and 0.7 parts silica powder. Silica play an important hole in the curing process Tests with fumed silica and non treated fumed silica showed considerable difference in the obtained final product We also developed a physical and chemical models of the setting process determine the time delay for onset of curing as a function of temperature and the profiles of the isotherms in the sample. In order to model the flow of the heat in laser-induced cunng we used theoretical approach to solve the time dependent heat equation in cylindrical coordinator. The data show the curing rate as function of temperature. Activation energy results were derived from differential scanning calorimetry (d.s.c.).

Experimental and theoretical study of local curing on thermosetting resins using a CO2 laser

We present a theoretical and experimental study of thermosetting resins used in thermal stereolithography. In usual practice, stereolithography makes use of photosensitive resins where HeCd (0.352 micrometers ) laser ultraviolet laser initiates the curing process. In this work we study the process of local curing through the application of infrared radiation, which has proved to be useful in a new technique for the making of prototypes by means of selective heating with a CO2 laser (10.6 micrometers ). The sample consists of a thermosetting resins (epoxy) with the curing agent (diethylene triamine) and a filler (silica). The ideal composition of the thermosetting resins has proved to be 10 parts epoxy, 1.4 part diethylene triamine (the curing agent) and 0.7 part silica powder. A physical theoretical model is applied for control of the parameters which influence the confinement of the curing in the irradiated bulk. A mathematical model was developed through the solution of the time dependent heat conduction equation in cylindrical co-ordinates, which enables the determination fo the behavior of curing in terms of irradiation conditions. An experimental analysis has determined the temperature range at which the curing process starts and the optimum silica concentration for efficient curing.

CARACTERIZAÇÃO DE AÇO INOXIDÁVEL AUSTENÍTICO PARA IMPLANTES CIRURGICOS MANUFATURADO POR DMLS.

* Contribuição técnica ao 72o Congresso Anual da ABM – Internacional e ao 17o ENEMET Encontro Nacional de Estudantes de Engenharia Metalúrgica, de Materiais e de Minas, parte integrante da ABM Week, realizada de 02 a 06 de outubro de 2017, São Paulo, SP, Brasil. CARACTERIZAÇÃO DE AÇO INOXIDÁVEL AUSTENÍTICO PARA IMPLANTES CIRURGICOS MANUFATURADO POR DMLS* Edgar Busato Junior Maria Aparecida Larosa André Luiz Jardini Munhoz Cecília Amélia de Carvalho Zavaglia

Infrared Laser Stereolithography

Infrared laser stereolithography is a new process of stereolithography, substantially different from those already existents; that uses an infrared laser (carbon dioxide laser) to localize the curing reaction of a thermo-sensitive materials building the desired three-dimensional (3D) shape. Being developed by Scarparo and collaborators at the University of Campinas (UNICAMP) in Brazil, since 1992 [1], and patented in 2002, this technique is to have commercial value, with thermo-sensitive material that must have useful properties for applications in rapid manufacturing and tooling, medicine, or other important fields. Certainly, further advances and process optimization are a part of the ongoing activities that are in consonance with a large number of programs around the world of very interesting work towards improvement of stereolithography process.