No abstract

The pursuit to reduce manufacturing costs and increase product quality has led industries to use commercial codes and appropriate material models to simulate a wide range of metal forming operations. This scenario has prompted a healthy discussion on the strategies to obtaining constitutive parameters able to yield accurate numerical predictions. Optimization‐based parameter identification techniques have opened completely new routes to determine material parameters for this class of forming problems. Notwithstanding, the most appropriate optimization strategy (or development of new ones) for the trinomial forming operation – constitutive model – constitutive parameters is still open to debate. This work highlights the important role that optimization strategies play to determine parameters of constitutive models. A brief description of gradient‐based, gradient‐free and hybrid optimization approaches is presented within the framework of parameter identification. Comparative studies and applications to classical and damaged material models are also discussed.

This study focuses in the synthesis of ceramic pigments based on the crystal structure of willemite (Zn2SiO4). The willemite obtained from the combination of commercial zinc oxide and rice husk ash is produced in a conventional ceramic process without the use of mineralizer agent and with the addition of cobalt oxide or nickel oxide as the source of chromophore ions. The synthesis temperature used was 1200°C. The characterization of pigments involves the use of X-ray diffraction and scanning electron microscopy. The pigments applied in matte enamel and sintered at 1100°C or 1200°C developed color between blue and beige. The construction of absorbance curves showed the color development behavior of each pigment. The results showed the possibility of obtaining willemite, from rice husk ash and the color development efficiency of the material, besides showing the interference of chromophore ion (Ni and Co) in color development.

Nanostructured materials have been largely studied in the last few years because they have a great potential to applications in different fields like physics, chemistry, biology, mechanic and medicine. Synthesis and characterization of nanostructured materials is a subject of great interest involving science, market, politicians, government and society. The nanostructured materials are in demand in biomedical area, mainly the bioceramics composed of calcium phosphates (Ca/P), which have an excellent biocompatibility and mineralogical characteristics similar to those of bones. The aim of this work was to optimize the method of powder synthesis of nanostructured calcium phosphate and of nanocomposites composed of calcium phosphate//SiO2n, containing 5, 10 and 15% (in volume) of nanometric silica (SiO2n). The results are expressed according to the method of synthesis, mineralogical and morphological characterization, and thermal behavior for the different compositions of the nanostructured powder synthesized.

In the ceramic coating industry, color and its stability influence the visual appearance of the product. These features account for the growing interest in obtaining pigments that are stable and may optimize the process. There are different synthesis routes to obtain pigments. Obtaining glass and its subsequent crystallization is an alternative proposed in the literature. This study focuses on the possible use the glass of the Li2O-ZrO2-SiO2 system as base glass and hematite as chromophore source. Different contents of hematite (1%, 2%, 3%), from the beneficiation process of metal sheets were used. The choice of composition aimed at facilitating the devitrification process for the formation of zirconia, which is often used as an encapsulating matrix in inorganic pigments. Results showed that glass synthesis is feasible and the effect of crystallization in the presence of hematite is favored, so an effective pigmenting effect is expected.