RESUMO O titânio comercialmente puro (Ti cp) é o principal material usado na fabricação dos implantes dentários osseointegráveis. Para melhorar os índices de sucesso do tratamento odontológico e reduzir o tempo de osseointegração dos implantes, foram desenvolvidas várias metodologias de tratamento da superfície dos implantes. Para caracterizar as morfologias das superfícies dos implantes são usadas as análises no microscópio eletrônico de varredura (MEV), rugosidade, molhabilidade, identificação de possíveis contaminantes, ensaios in-vitro de culturas de células e in-vivo com animais. Entre as técnicas citadas, as mais usadas são as análises no MEV, as medidas dos parâmetros da rugosidade e da molhabilidade. Alguns trabalhos disponíveis na literatura sugerem a caracterização somente do valor de Ra sem apresentar uma explicação para a escolha deste parâmetro. No presente trabalho é feita a proposta de um modelo matemático para quantificar a relação entre os vários parâmetros da rugosidade 3D (Ra, Rq, Rz, Rms, Pico, Vale, PV, R3z e Smax) com a molhabilidade e a energia de superfície do Ti cp com dois tamanhos de grão (micrométricos e sub-micrométricos) e submetidos ao tratamento com ácido. Os resultados mostraram que para o nível de confiança de 95%, as propriedades das superfícies do Ti cp tratados com ácido são mais influenciadas pelos parâmetros de rugosidade Ra e Rms.

ABSTRACT Commercially pure titanium (cp Ti) is the main material used in the manufacture of dental implants. To improve the success rate of dental implant treatment some dental implant surface treatment methodologies have been developed. To characterize the surfaces of dental implants are used scanning electron microscope (SEM) analysis, roughness and wettability measurements, in-vitro cell culture and in-vivo animal experiments. Among the techniques cited, the simplest are SEM analyzes, of roughness and wettability measurements. Some papers available in the literature show values of surface roughness parameters and suggest the use of the Ra value without presenting any explanation for the choice of this parameter. In the present work, a mathematical model is proposed to quantify the relationship between some parameters of the 3D roughness (Ra, Rq, Rz, Rms, Peak, Vale, PV, R3z and Smax) with the wettability and surface energy of cp Ti with two grain sizes (micrometric and sub-micrometric). The results showed that the properties of the acid treated cp Ti surfaces are more influenced by the roughness parameters Ra and Rms.

The response to ballistic impact of alumina-ultra high molecular weight polyethylene (UHMWPE) composites with different relative concentrations of alumina was investigated. The impact tests were carried out at subsonic speed using a compressed air system. The results showed that the depth of penetration (DOP) in a Medium Density Fiberboard (MDF) bulkhead protected by a disk of the composite decreased with increasing concentration of alumina in the composite. Scanning electron microscopy (SEM) images of composites with 80 %, 85 % and 95 % alumina showed transgranular, intergranular and ductile fracture mechanisms.

Natural fiber reinforced polymer composites have recently been investigated as a component of multilayered armor system (MAS). These composites were found to present advantages when replacing conventional high strength synthetic aramid fabric laminate composite (KevlarTM, with same thickness, as MAS second layer. Continuous and loose natural fibers were up to now mostly used to reinforce these ballistic composites. Only two natural fabrics reinforced polymer composite were so far used with same purpose. Therefore, this work investigated the possibility of substituting KevlarTM for three other natural fabrics, based on mallow and jute fibers, as reinforcement of epoxy composites. Fabrics made of either pure mallow, or 70%mallow/30% jute or 50%mallow/50% jute fibers were separately mixed with epoxy to produce laminate composite plates. These plates were set as second layer of Al2O3/Nb2O5 front ceramic MAS, that were ballistic tested against relatively high energy 7.62 mm ammunition. Indentation depth values caused by the bullet penetration in clay witness, simulating human body behind the MAS, were always found to be below the safety standard limit. These indentation values were similar to those obtained in MAS with KevlarTM as second layer. However, significant economical advantages favor the investigated natural fabric composites over the synthetic Kevlar.

This study carried out the microstructural characterization, by light microscopy, of sintered SiC in the presence of liquid phase at temperatures of 1800, 1850 and 1900 ºC, added with Al2O3 and Y2O3 as well with Al2O3-YAG composite in the proportions of 5, 10 and 15% by weight. It was possible to observe the formation of microstructural patterns resulting from the heterogeneous segregation of the additives, such observation is associated to the pulling of additives during the initial stage of ceramography. Two ceramographic paths were followed: method I - surface grinding followed by manual polishing and method II - automatic grinding and polishing. In order to compare the two techniques the analysis of 3D roughness by light interferometry and the Vickers microhardness test were used. It was concluded by the analysis of variance with 95% confidence that the degree of finishing obtained by both methods allowed the adequate microstructural characterization, as well as, to meet the requirements established by the ASTM C1327-15 standard for hardness test.