Papers by Keyword: Ceramic

Abstract: This article describes a method for measuring the dielectric constant and magnetic permeability of alumina powder (corundum) in the frequency range of 8-12 GHz. The results of studies of permeability and permittivity using a segment of a coaxial transmission line depending on the size of corundum particles are presented.

Abstract: This paper presents a verification of technology aspects for improvement of field effect capacity type gas sensor parameters by using laser micromilling technique for fabrication ceramic surface mounting device (SMD) package and microheater for sustentation working temperature of metal-insulator-semiconductor structure (MIS structure). Innovative claims include: demonstration of flexible opportunities for new digital fabrication process flows based on laser micromilling tech: fast design of SMD sensor 3-D model, flexible changing topology of microheater, thick and thin film technology combination for reducing of power consumption. The results show possibility to fast fabrication functional sensor in customer ceramic SMD package with base 9x9 mm with twice reduced power consumption and improving mechanical properties compare with classical metal-glass microelectronic packages using before for such type sensors.

Abstract: This article presents the technological aspects of experiments on the stable topological patterns formation from thin films of platinum on ceramic membranes. Platinum thin films were deposited by magnetron sputtering on a clean or pre-activated laser ceramics surface. After the deposition of platinum films, the method of various short-term laser irradiation was attempted to form a topological pattern. The results are discussed.

Abstract: This paper presents a modeling of technology aspects for fabrication ceramic microelectromechanical systems (MEMS) microhotplate and surface mounting device (SMD) packaging for (MOX) gas sensors applications. Innovative claims include: demonstration of flexible opportunities for new fabrication process flows based on laser micromilling tech; modeling of power consumption MEMS microhotplate depending on the thickness and topology; demonstration of necessity changing thick film technology of metallization to vacuum sputtering by reducing of power consumption. The results show possibility to fast fabrication of different topologies for ceramic MEMS microhotplate in form-factor of SOT-23 type SMD package.

Abstract: Ceramic composites is playing crucial role to accomplish highly efficiently and cost effective equipment for aerospace industry. The instigation of ceramics into aircraft industry is a promising step towards virtuous future. Ceramics has a key role in innovation of highly competent material for space travel which is highly economical and environmentally sustainable. Advancement in making fuel efficient engines are necessity in present scenario due to the harmful emissions releases in the environment by burning of fuel to power up engine. The high temperature application of composites makes it very attractive for aerospace applications. This light weight material has potential to thrust spacecraft upto ten times quicker with the identical fuel consumption, therefore significantly depreciating size of vehicle and increasing travel distance. The implementation of ceramics into jet engines and turbines increase the efficiency of engine due to its lighter weight and better thermal capabilities. A jet engine employing ceramic composites has manifest 15% more fuel saving when compared to the simple nickel based alloys. Hence, ceramic composites can replace nickel based alloys which has been a promising candidate for the engines of commercial aircrafts. Some disadvantages has been also discussed that is brittle failure and limited thermal and shock resistance.

Abstract: A series of Sm_0.5Sr_0.5CoO₃-CeO₂ ceramics formed by solid state-reaction method have been systematically investigated. The effects of doping the Sm site of Sm_0.5Sr_0.5CoO₃ with Ce⁴⁺ on the structural, spectral reflectance, and thermal radiation properties were also explored. The modification of the initial phase takes place can be ascribed to the dissolution of Ce from initial CeO₂ into the perovskite structure. The conductivity behavior depends critically on the Ce doping level, as was demonstrated that the recombination of holes (from Sm_0.5Sr_0.5CoO₃) and electrons (from ceria ion) could decrease electrical conductivity. Sm_0.5Sr_0.5CoO₃-CeO₂ ceramics showed continuously adjustable conductivity and infrared emittance, opening up possible applications in solar thermal conversion or thermosensitive conductivity.

Abstract: The paper presents the method of a microscopic study of ceramic chips which can be useful in the analysis of physical phenomena regarding machining of ceramic materials. The analyzed chips were obtained on the milling machine tool from the Al2O3 based ceramic material. The measurements were performed using focus-variation technique (FVT). The InfiniteFocus Real3D microscope from Alicona Imaging company was applied. The paper mainly focuses on the methodology of measurements and the application of microscope’s software tools which can be used in the analysis of chips' 3D scans. The conditions of measurement process are discussed on the basis of the results of exemplary measurements of ceramic chips.

Abstract: The paper presents and experimental study upon several types of materials used for dental works (especially prosthetic works) after prolonged use (over 10 years). The issues that lead to the necessity of changing the prosthetic works are the results of multiple types of wear. Our aim is to determine the extension of damage by digital microscopy, probable causes and analyze the benefits and disadvantages of the most used materials in prosthetic works.

Abstract: The modified calcium oxide partially stabilized zirconia ceramics were fabricated using ZrO₂ powder as raw materials, CaO as stabilizer, and nanometre zirconia as modification agent. The relationship between additive amount of nanometre zirconia and the performance of Ca-PSZ ceramics were researched via testing the physical properties, analyzing mineral phase composition, and observing microstructure of the samples. The results show that the introduction of nanometre zirconia powder has a significant effect on the physical properties of Ca-PSZ, with an addition of 8wt%, bulk density was up to 5.08 g/cm³, and the compressive strength reached 381 MPa. Compared with the unmodified Ca-PSZ sample, the porosity of the modified Ca-PSZ samples decreased by 40%, and the compressive strength increased by 70%. The introduction of nanometre zirconia has an inhibitory effect on the abnormal growth of zirconia grains and improves the densification of the Ca-PSZ ceramics. Through the formation of intragranular structure, nanometre zirconia can induce transgranular fracture and weaken crystalline fracture, thereby increasing the strength of the Ca-PSZ ceramics.

Abstract: Mae Moh lignite bottom ash was utilized as the main component in the fabrication of lightweight ceramic formulations. The amount of 50-80 wt.% bottom ash was successfully utilized to produce ceramics at sintering temperatures between 900 and 1200°C. Waste glass was used as a flux for the sintering process. Bottom ash was carefully sieved into three different particle sizes; small, medium and large. The different particle sizes were used in the ceramic fabrication to investigate for the densification behavior. Overall, porosity and water absorption of the fabricated ceramics decreased with increasing sintering temperature. Sintering at 1125°C resulted in the most densified ceramics which retained good physical appearance without sample distortion or melting.