The development of photosensitive ceramic slurries for vat photopolymerization (stereolithography... more The development of photosensitive ceramic slurries for vat photopolymerization (stereolithography or digital light processing) has received much effort in recent years. However, many of these ceramic suspensions have high viscosity and they are suitable for use only on equipment, specialized in ceramic additive manufacturing. In this work, ceramic manufacturing using photocurable slurries was tested in a low-cost vat photopolymerization printer and in silicone moulds for UV-casting replication, with the latter approach still scarcely explored in the literature. Both processes were able to produce ceramic parts. The UV-casting replication was able to work with more viscous photocurable ceramic slurries and proved more suitable for the manufacturing of ceramic parts with larger cross-sections, providing pieces with improved flexural strength to those produced by additive manufacturing. This work presents the possibility of UV-casting photosensitive slurries to manufacture ceramics, an...
This study aimed to develop bone regenerative therapeutic strategies, based on the addition of bo... more This study aimed to develop bone regenerative therapeutic strategies, based on the addition of bone marrow stromal cells (BMSC) on bioglass/collagen (BG/COL) scaffolds. For this purpose, an in vivo study was conducted using tissue response of the BG/COL scaffolds combined with BMSC in a critical-size defects. Wistar rats were submitted to the surgical procedure to perform the cranial critical size bone defects and distributed in four groups (20 animals per group): Control Group (CG) (rats submitted to the cranial bone defect surgery without treatment), Bioglass Group (BG) (rats treated with BG), BG/COL Group (rats treated with BG/COL) and Bioglass/Collagen and BMSC Group (BG/COL/BMSC) (rats treated with BG/COL scaffolds enriched with BMSCs). Animals were euthanized 15 and 30 days after surgery. Scanning electron microscopy, histopathological and immunohistochemistry analysis were used. SEM analysis demonstrated that porous scaffolds were obtained, and Col fibers were successfully im...
Nowadays, environmental concerns are causing companies to seek reduce the environmental impacts c... more Nowadays, environmental concerns are causing companies to seek reduce the environmental impacts caused by them, while improving product quality and manufacturing processes. Therefore, much research is being developed in the machining area to examine the actual damage to the environment by utilizing different methods of lubrifi cation and cooling. This study aimed to analyze the surface roughness of the machined part and the wear of the grinding wheel in the fl at grinding of alumina ceramics with two methods of coolinglubrifi cation: The conventional method with a fl ow rate of 27.5 L/min and the method of the minimum quantity of lubrifi cation (MQL) at 100 mL/h. With the obtained results it’s possible to say that, for the same machining parameters of MQL and conventional techniques, the MQL technique used a much smaller amount of fl uid and assured good results for the diametral wear of the grinding wheel. However, the superfi cial roughness of the piece was worse for the MQL metho...
Com o grande crescimento tecnológico e a necessidade de melhoria, um dos materiais que ganhou uma... more Com o grande crescimento tecnológico e a necessidade de melhoria, um dos materiais que ganhou uma grande gama na área da engenharia mecânica é a cerâmica, pois possui vantagens físico-químicas e propriedades mecânicas significativas sobre o aço. Entretanto, sua usinagem é um processo difícil e delicado, que requer ainda uma grande atenção em relação ao seu estudo. Assim, o processo de retificação é um dos métodos que tem apresentado bons resultados, porém um grande problema acerca de tal processo é o uso excessivo de fluidos de corte, o que se tornou uma preocupação mundial, já que os fluidos apresentam graves problemas socioambientais, além disso, o fluido de corte é responsável por uma grande parte do custo final do processo, provocando, desse modo, um grande interesse em pesquisas referentes a métodos alternativos de forma a reduzir o consumo e melhorar as características do fluido de corte utilizado. Este trabalho visa comparar duas técnicas de lubri-refrigeração, o método conve...
Resumo - Este trabalho objetivou as investigacoes in vitro e em microscopia eletronica de varredu... more Resumo - Este trabalho objetivou as investigacoes in vitro e em microscopia eletronica de varredura (MEV) de um scaffold manufaturado com PMMA (Polimetilmetacrilato) e HAp (Hidroxiapatita). A carboximetilcelulose (CMC) foi utilizada na forma de gel como agente porogenico, a fim de torna-lo bio mimeticamente viavel como substituto osseo. Foram utilizadas para os ensaios in vitro celulas VERO, uma linhagem celular tipo fibroblastos. Foram realizados ensaios de citotoxicidade indireta e direta. Os resultados indicaram que as diferentes amostras de PMMA poroso com HAp e PMMA poroso nao apresentaram toxicidade direta ou indireta. Atraves das imagens realizadas em MEV tambem se pode observar o crescimento de celulas na superficie do material e em direcao aos poros da matriz. A analise macroestrutural dos poros das matrizes porosas tambem obtidas pela microscopia eletronica de varredura (MEV) demonstrou em uma caracterizacao inicial do material que este apresentou caracteristicas bio mimeticas sendo eleito como substitutos osseos. A media obtida do tamanho dos poros foi de aproximadamente 250μm.
This paper presents the development of an advanced ceramic material for manufacturing aerostatic ... more This paper presents the development of an advanced ceramic material for manufacturing aerostatic porous bearing. The results show that there is homogeneous distribution of the pores in the alumina matrix by using different concentrations of the added component (sucrose). The average pore diameter remained around 0.14 µm and respective porosity around 28%, with small standard deviation. The mathematical model of the aerostatic porous bearing is presented, and numerical results indicate that the parameter related to porous medium (Г) strongly affects the resultant bearing load capacity and stiffness. Considering the experimental and numerical results, the porous matrix obtained with 40% of sucrose concentration is more suitable for the aerostatic porous bearing application in study.
Wear resistance is a fundamental property which defines the lifetime of cutting tools, but the in... more Wear resistance is a fundamental property which defines the lifetime of cutting tools, but the investigation of wear performance of alternative hard materials for traditional WC-Co composites are recent. The present work evaluated the pin-on-disk wear behavior and mechanical properties, i.e., hardness and fracture toughness of spark plasma sintered Al2O3 matrix composites with additions of 5, 15, 25 or 30%wt of niobium carbide NbC. The wear resistance was observed to increase as a function of the NbC content, even though the hardness reached a plateau at 25%wt NbC. The composite behavior was compared to that of other alumina composite tool materials proving to be a promising material for applications such as ceramic cutting tools. The composition A95N5 presented the best combination of values of wear rate: 8.9 mm3/N.m, hardness equal to (17.36±1.72) GPa and fracture toughness of (3.2±0.6) MPa. m1/2.
O objetivo deste estudo foi avaliar a influencia do processamento e adição de diferentes concentr... more O objetivo deste estudo foi avaliar a influencia do processamento e adição de diferentes concentrações de nanotubos TiO2 (TiO2 nt) (0, 1, 2 e 5% em volume) em Y-TZP experimental quanto à confiabilidade, comparada à Y-TZP comercial (e.max ZirCad, Ivoclar/Vivadent). Todas as etapas da confecção das Y-TZPs experimentais foram controladas: mistura do pó, secagem, granulação, conformação e sinterização. Espécimes (12 ø x 1,1mm) foram obtidos para cada grupo (n28). A Y-TZP comercial foi preparada para se obter o mesmos formatos e dimensões (pós sinterização) dos espécimes experimentais. Todos espécimes foram submetidos ao teste de flexão biaxial (RFB) até a fratura, de acordo com as normas da ISO 6872, 2016. Dados de RFB foram submetidos aos testes de ANOVA e Tukey (a0,05). Os dados de RFB também foram utilizados para o cálculo do módulo de Weibull (m) e resistência característica (o) de cada grupo (Weibull 7++, Reliasoft, Tucson, USA). Cinco espécimes de cada grupo foram analisados em Microscopia Eletrônica de Varredura (MEV) para análise fractográfica. RFB: Y-TZP comercial apresentou os maiores valores (p<0,05), diferindo dos grupos de Y-TZP experimentais. m e o: os grupos de Y-TZP experimentais obtiveram os maiores valores em comparação à Y-TZP comercial, sendo que a Y-TZP 0% de TiO2 nt obteve os maiores valores, diferindo das concentrações 1, 2 e 5%. A análise fractográfica mostrou padrões de fratura similares entre os grupos. O controle do processamento da Y-TZP aumentou a confiabilidade populacional do material.Palavras-chave: Cerâmica. Nanotubos. Engenharia Biomédica.
This research uses model based design to evaluate and realize the complex motion of the lower pla... more This research uses model based design to evaluate and realize the complex motion of the lower plates that define balls motion during grinding. The Model In the Loop (MIL) was performed through the machine model generated using ADAMS and then exported to Simulink. For a prior evaluation of the machining, the grinding tracks were built through the simulation results performing Software In the Loop (SIL). The balls grinding was performed by an Arduino connected to the machine, finishing Hardware In the Loop (HIL). The technique integrated the simulation and balls grinding processes, increasing the simplicity and reducing the development time.
The development of photosensitive ceramic slurries for vat photopolymerization (stereolithography... more The development of photosensitive ceramic slurries for vat photopolymerization (stereolithography or digital light processing) has received much effort in recent years. However, many of these ceramic suspensions have high viscosity and they are suitable for use only on equipment, specialized in ceramic additive manufacturing. In this work, ceramic manufacturing using photocurable slurries was tested in a low-cost vat photopolymerization printer and in silicone moulds for UV-casting replication, with the latter approach still scarcely explored in the literature. Both processes were able to produce ceramic parts. The UV-casting replication was able to work with more viscous photocurable ceramic slurries and proved more suitable for the manufacturing of ceramic parts with larger cross-sections, providing pieces with improved flexural strength to those produced by additive manufacturing. This work presents the possibility of UV-casting photosensitive slurries to manufacture ceramics, an...
This study aimed to develop bone regenerative therapeutic strategies, based on the addition of bo... more This study aimed to develop bone regenerative therapeutic strategies, based on the addition of bone marrow stromal cells (BMSC) on bioglass/collagen (BG/COL) scaffolds. For this purpose, an in vivo study was conducted using tissue response of the BG/COL scaffolds combined with BMSC in a critical-size defects. Wistar rats were submitted to the surgical procedure to perform the cranial critical size bone defects and distributed in four groups (20 animals per group): Control Group (CG) (rats submitted to the cranial bone defect surgery without treatment), Bioglass Group (BG) (rats treated with BG), BG/COL Group (rats treated with BG/COL) and Bioglass/Collagen and BMSC Group (BG/COL/BMSC) (rats treated with BG/COL scaffolds enriched with BMSCs). Animals were euthanized 15 and 30 days after surgery. Scanning electron microscopy, histopathological and immunohistochemistry analysis were used. SEM analysis demonstrated that porous scaffolds were obtained, and Col fibers were successfully im...
Nowadays, environmental concerns are causing companies to seek reduce the environmental impacts c... more Nowadays, environmental concerns are causing companies to seek reduce the environmental impacts caused by them, while improving product quality and manufacturing processes. Therefore, much research is being developed in the machining area to examine the actual damage to the environment by utilizing different methods of lubrifi cation and cooling. This study aimed to analyze the surface roughness of the machined part and the wear of the grinding wheel in the fl at grinding of alumina ceramics with two methods of coolinglubrifi cation: The conventional method with a fl ow rate of 27.5 L/min and the method of the minimum quantity of lubrifi cation (MQL) at 100 mL/h. With the obtained results it’s possible to say that, for the same machining parameters of MQL and conventional techniques, the MQL technique used a much smaller amount of fl uid and assured good results for the diametral wear of the grinding wheel. However, the superfi cial roughness of the piece was worse for the MQL metho...
Com o grande crescimento tecnológico e a necessidade de melhoria, um dos materiais que ganhou uma... more Com o grande crescimento tecnológico e a necessidade de melhoria, um dos materiais que ganhou uma grande gama na área da engenharia mecânica é a cerâmica, pois possui vantagens físico-químicas e propriedades mecânicas significativas sobre o aço. Entretanto, sua usinagem é um processo difícil e delicado, que requer ainda uma grande atenção em relação ao seu estudo. Assim, o processo de retificação é um dos métodos que tem apresentado bons resultados, porém um grande problema acerca de tal processo é o uso excessivo de fluidos de corte, o que se tornou uma preocupação mundial, já que os fluidos apresentam graves problemas socioambientais, além disso, o fluido de corte é responsável por uma grande parte do custo final do processo, provocando, desse modo, um grande interesse em pesquisas referentes a métodos alternativos de forma a reduzir o consumo e melhorar as características do fluido de corte utilizado. Este trabalho visa comparar duas técnicas de lubri-refrigeração, o método conve...
Resumo - Este trabalho objetivou as investigacoes in vitro e em microscopia eletronica de varredu... more Resumo - Este trabalho objetivou as investigacoes in vitro e em microscopia eletronica de varredura (MEV) de um scaffold manufaturado com PMMA (Polimetilmetacrilato) e HAp (Hidroxiapatita). A carboximetilcelulose (CMC) foi utilizada na forma de gel como agente porogenico, a fim de torna-lo bio mimeticamente viavel como substituto osseo. Foram utilizadas para os ensaios in vitro celulas VERO, uma linhagem celular tipo fibroblastos. Foram realizados ensaios de citotoxicidade indireta e direta. Os resultados indicaram que as diferentes amostras de PMMA poroso com HAp e PMMA poroso nao apresentaram toxicidade direta ou indireta. Atraves das imagens realizadas em MEV tambem se pode observar o crescimento de celulas na superficie do material e em direcao aos poros da matriz. A analise macroestrutural dos poros das matrizes porosas tambem obtidas pela microscopia eletronica de varredura (MEV) demonstrou em uma caracterizacao inicial do material que este apresentou caracteristicas bio mimeticas sendo eleito como substitutos osseos. A media obtida do tamanho dos poros foi de aproximadamente 250μm.
This paper presents the development of an advanced ceramic material for manufacturing aerostatic ... more This paper presents the development of an advanced ceramic material for manufacturing aerostatic porous bearing. The results show that there is homogeneous distribution of the pores in the alumina matrix by using different concentrations of the added component (sucrose). The average pore diameter remained around 0.14 µm and respective porosity around 28%, with small standard deviation. The mathematical model of the aerostatic porous bearing is presented, and numerical results indicate that the parameter related to porous medium (Г) strongly affects the resultant bearing load capacity and stiffness. Considering the experimental and numerical results, the porous matrix obtained with 40% of sucrose concentration is more suitable for the aerostatic porous bearing application in study.
Wear resistance is a fundamental property which defines the lifetime of cutting tools, but the in... more Wear resistance is a fundamental property which defines the lifetime of cutting tools, but the investigation of wear performance of alternative hard materials for traditional WC-Co composites are recent. The present work evaluated the pin-on-disk wear behavior and mechanical properties, i.e., hardness and fracture toughness of spark plasma sintered Al2O3 matrix composites with additions of 5, 15, 25 or 30%wt of niobium carbide NbC. The wear resistance was observed to increase as a function of the NbC content, even though the hardness reached a plateau at 25%wt NbC. The composite behavior was compared to that of other alumina composite tool materials proving to be a promising material for applications such as ceramic cutting tools. The composition A95N5 presented the best combination of values of wear rate: 8.9 mm3/N.m, hardness equal to (17.36±1.72) GPa and fracture toughness of (3.2±0.6) MPa. m1/2.
O objetivo deste estudo foi avaliar a influencia do processamento e adição de diferentes concentr... more O objetivo deste estudo foi avaliar a influencia do processamento e adição de diferentes concentrações de nanotubos TiO2 (TiO2 nt) (0, 1, 2 e 5% em volume) em Y-TZP experimental quanto à confiabilidade, comparada à Y-TZP comercial (e.max ZirCad, Ivoclar/Vivadent). Todas as etapas da confecção das Y-TZPs experimentais foram controladas: mistura do pó, secagem, granulação, conformação e sinterização. Espécimes (12 ø x 1,1mm) foram obtidos para cada grupo (n28). A Y-TZP comercial foi preparada para se obter o mesmos formatos e dimensões (pós sinterização) dos espécimes experimentais. Todos espécimes foram submetidos ao teste de flexão biaxial (RFB) até a fratura, de acordo com as normas da ISO 6872, 2016. Dados de RFB foram submetidos aos testes de ANOVA e Tukey (a0,05). Os dados de RFB também foram utilizados para o cálculo do módulo de Weibull (m) e resistência característica (o) de cada grupo (Weibull 7++, Reliasoft, Tucson, USA). Cinco espécimes de cada grupo foram analisados em Microscopia Eletrônica de Varredura (MEV) para análise fractográfica. RFB: Y-TZP comercial apresentou os maiores valores (p<0,05), diferindo dos grupos de Y-TZP experimentais. m e o: os grupos de Y-TZP experimentais obtiveram os maiores valores em comparação à Y-TZP comercial, sendo que a Y-TZP 0% de TiO2 nt obteve os maiores valores, diferindo das concentrações 1, 2 e 5%. A análise fractográfica mostrou padrões de fratura similares entre os grupos. O controle do processamento da Y-TZP aumentou a confiabilidade populacional do material.Palavras-chave: Cerâmica. Nanotubos. Engenharia Biomédica.
This research uses model based design to evaluate and realize the complex motion of the lower pla... more This research uses model based design to evaluate and realize the complex motion of the lower plates that define balls motion during grinding. The Model In the Loop (MIL) was performed through the machine model generated using ADAMS and then exported to Simulink. For a prior evaluation of the machining, the grinding tracks were built through the simulation results performing Software In the Loop (SIL). The balls grinding was performed by an Arduino connected to the machine, finishing Hardware In the Loop (HIL). The technique integrated the simulation and balls grinding processes, increasing the simplicity and reducing the development time.
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