Abstract Vat photopolymerization (VP) stands out among ceramic additive manufacturing processes for its ability to print sub-100 micrometer complex features. One of the main challenges of this process is the preparation of a homogeneous and stable ceramic slurry with a high solid load and low viscosity. In this work, different dispersants and resins were tested, aiming to provide a solvent-free slurry suitable for DLP additive manufacturing. Disperbyk-111 and PEGDA 250 stood out in the tests, providing a 40 vol% ceramic slurry with no noticeable sedimentation and viscosity of 2.3 Pa.s at 30 s-1 despite the relatively high specific surface area (15 m2/g) of the 3Y-TZP powder used compared to powders usually used for VP slurries. The adsorption of Disperbyk-111 on ceramic particles surface was investigated by FTIR. Finally, ceramic bodies were 3D printed, debound and sintered at 1500 ºC for 2 h, confirming the ability to manufacture detailed dense ceramic parts.

Abstract Additive manufacturing processes have been developed over the last decades, especially vat photopolymerization (VP) processes, due to its simplicity and speed. The objective of this paper is to characterize commercial VP resins widely used for technical applications. Thus, test specimens were printed by Digital Light Processing and subjected to tensile, compression, flexural, hardness, and inorganic composition analyses. The resin with the highest resistance and hardness (containing 0.6 vol% of inorganics load) reached 53 MPa in tension, 110 MPa in compression, 79 MPa in bending, and 82.3 Shore D, which is comparable to injected polymers. A case study was made, replacing the injected gears of a reducer by printed ones and comparing the finite element analysis with resin properties. The characterization and case study results encourage the expansion of VP processes in the manufacturing of products in several industries and service sectors, as well as the development of new composite resins.

RESUMO A manufatura aditiva (AM) tem proporcionado grande versatilidade na geometria e em materiais, permitindo que novos produtos e processos sejam criados em diversas áreas. Deposição Direta de Energia (DED) é um processo de manufatura aditiva criado em 1995 que permite a fabricação de componentes metálicos e cerâmicos com alta densidade sem a necessidade de etapas posteriores, a exemplo de sinterização ou infiltração. Este artigo objetiva o estudo do estado da arte do processo DED relacionado à cerâmica. Partindo da geração de uma linha do tempo da manufatura aditiva, que inclui os marcos relacionados à Deposição Direta de Energia, foi realizada uma revisão sistemática em que os artigos foram agrupados em 3 categorias: revestimento cerâmico, AM de cerâmica e AM de compósitos com reforços cerâmicos. Para cada categoria foram analisados, classificados e resumidos aspectos referentes às matérias primas, substratos de deposição, principais aplicações, parâmetros de processo e propriedades. A maior parte dos trabalhos referente à categoria da manufatura aditiva cerâmica está relacionada com a fabricação da alumina, sendo que propriedades já são similares às produzidas por processos convencionais de manufatura. Trabalhos recentes utilizaram a vibração ultrassônica para homogeneizar o material em processo, reduzindo trincas e melhorando as propriedades mecânicas. A categoria AM de compósitos com reforços cerâmicos tem sido empregada para criar materiais compósitos com gradiente funcional de elevada dureza, enquanto que a categoria de revestimentos cerâmicos tem sido majoritariamente utilizada para fabricação de revestimentos biocompatíveis com elevada dureza e baixa taxa de desgaste. De modo geral, é certo que o advento dessa tecnologia vai ocupar fatia importante da manufatura cerâmica.

ABSTRACT Additive manufacturing (AM) has provided huge versatility in geometry and materials, allowing new products and processes in several areas to be created. Laser Engineered Net Shaping (LENS) is an additive manufacturing process created in 1995 that allows building high-density metals and ceramics parts with no need for further operation. This manuscript aims to study the scientific literature about the process of Laser Engineered Net Shaping related to ceramics. After a systematic review, the articles were grouped into three categories: ceramic coating and AM of ceramics and AM of composites with ceramic reinforcement. Raw materials, substrates, applications, process parameters, and the obtained properties were analyzed and summarized for each group. Most of the additive manufacturing of ceramic parts are related to alumina, which present similar properties when compared to the traditionally manufactured ones. Recent works have the aid of an ultrasonic vibration to homogenize the in-process material, reduce cracks and improve mechanical properties. The additive manufacturing of composites with ceramic reinforcement has been used to create functionally graded composites materials with increased hardness, while the ceramic coating has been employed to manufacture biocompatible coating with increased hardness and low wear rate. Moreover, an additive manufacturing timeline including Laser Engineered Net Shaping landmarks is presented.

Planetary ball mills are able to perform dry and wet grinding. Most experimental analyses and computer simulations in this field are mainly about dry grinding. In order to empirically evaluate the wet grinding process, test grindings benches were manufactured, calcined alumina powder was ground, and the particle distribution analyzed. Effects of the media geometry (size and shape) on particle distribution, morphology, and phase composition of ground alumina were investigated. Smaller media leads to smaller particle size and cylindrical media provides a poor grinding performance but its product has the narrower particle size distribution. Alumina showed no phase change in the grinding tests. The experiments presented in this study can be used as an aid in the proper choice of grinding media or even to validate emerging models capable of predicting breakage in wet grinding.