Grinding of ceramic materials: a model for energy consumption and force transformation

1994 ◽  
Vol 16 (1) ◽  
pp. 72-73
Keyword(s):  
Energy Consumption ◽  
Ceramic Materials ◽  
Force Transformation

Oxygen Enrichment in Combustion Processes: Comparative Experimental Results From Several Application Fields

1991 ◽  
Vol 113 (2) ◽  
pp. 122-126
Author(s):  
M. De Lucia
Keyword(s):  
Energy Consumption ◽  
Energy Savings ◽  
Copper Alloys ◽  
Ceramic Materials ◽  
Oxygen Enrichment ◽  
Experimental Results ◽  
Ferrous Metals ◽  
Definition Of ◽  
Application Fields ◽  
Combustion Processes

The effects of using oxygen to partially or wholly replace fuel air in small-size melting furnaces were studied over a range of application fields. Following definition of the useful parameters, testing was conducted on furnaces for melting glass, ferrous metals (pigiron), nonferrous metals (copper alloys), and ceramic materials. In all cases, oxygen-enrichment was found to provide significant energy savings, as well as notable advantages in terms of both plant output and energy consumption.

scholarly journals Pozzolanic mortars based on waste building materials for the restoration of historical buildings

2012 ◽  
Vol 18 (2) ◽  
pp. 147-154 ◽  
Author(s):  
Snezana Pasalic ◽  
Snezana Vucetic ◽  
Dmitar Zoric ◽  
Vilma Ducman ◽  
Jonjaua Ranogajec
Keyword(s):  
Energy Consumption ◽  
Natural Resources ◽  
Building Materials ◽  
Ceramic Materials ◽  
Waste Materials ◽  
Historical Buildings ◽  
Environmental Aspects ◽  
Culture Heritage ◽  
Reduction Of Energy Consumption ◽  
Clay Materials

The environmental aspects of waste building materials have been of great interest in recent years. For the sector of building materials this means increased recycling, reduction of energy consumption and natural resources preservation. This also presents an important contribution in the field of environmental protection. The work deals with the development of pozzolanic mortars made of waste building materials, ground red structure bricks and raw clay materials of inadequate characteristics for the production of ceramic materials. Based on the results of historical mortar characterizations, a group of mortars with specific characteristics (satisfied durability, good compatibility with a historical mortar) was prepared. The potential of the waste materials and domestic clay materials application in the production of pozzolanic mortars was confirmed. In addition to the waste management, pozzolanic mortars were designed taking into account the existing conventions in the area of culture heritage.

Process Stability and Energy Efficiency of the Grinding Process of High Performance Materials

2012 ◽  
Author(s):  
E. Uhlmann ◽  
F. Sammler ◽  
F. Heitmueller ◽  
L. Hochschild ◽  
C. Sammler
Keyword(s):  
Energy Consumption ◽  
Machine Tools ◽  
High Performance ◽  
Rolling Bearing ◽  
Ceramic Materials ◽  
Manufacturing Processes ◽  
Full Potential ◽  
Process Stability ◽  
Bearing Rings ◽  
External Cylindrical Grinding

The application of high performance materials can lead to enhanced product properties. The associated challenging material properties set higher demands on the manufacturing processes. However, the ever-present demand for cost reduction of the manufacturing processes conflicts with the continuously increasing demands on product quality. In principle, higher surface quality results in higher energy consumption. Higher geometrical demands in combination with difficult to cut materials lead to increasingly complex machine tool and subsystem solutions, which also contribute to the higher energy consumption. However, the full potential of a process is often not utilized in order to ensure that damages to the workpiece at the end of cost intensive and long value chains are avoided. This leads to the situation that complex machine tools equipped with high performance tools operate under significantly reduced productivity. This means that the production process itself must be reliable in particular during high performance machining. In this paper, various grinding strategies were regarded in terms of possible increase in productivity and process stability. Furthermore a nonconventional option of flexible machining is presented. It will be shown that the process of speed stroke grinding of ceramic materials can be used as a highly productive alternative to reciprocating grinding and external cylindrical grinding with grooved cBN-grinding-wheels for example in the grinding of rolling bearing rings. The machining of high performance materials with simple machine concepts, such as robots, is presented with regards to more flexibility and at the same time machine accuracies comparable to these machine tools.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

Stress-Induced Ordering in Y203-Stabilized Tetragonal Zr02

1985 ◽  
Vol 43 ◽  
pp. 222-223
Author(s):  
J. Y. Koo ◽  
M. P. Anderson
Keyword(s):  
Electron Diffraction ◽  
Ionic Conduction ◽  
Electron Diffraction Study ◽  
Ceramic Materials ◽  
Bright Field Image ◽  
Transformation Toughening ◽  
Ion Milling ◽  
Thin Foils ◽  
Carbon Coated ◽  
Convergent Beam

Tetragonal Zr02 has been used as a toughening phase in a large number of ceramic materials. In this system, complex diffraction phenomena have been observed and an understanding of the origin of the diffraction effects provides important information on the nature of transformation toughening, ionic conduction, and phase destabilization. This paper describes the results of an electron diffraction study of Y203-stabilized, tetragonal Zr02 polycrystals (Y-TZP).Thin foils from the bulk Y-TZP sample were prepared by careful grinding and cryo ion-milling. They were carbon coated and examined in a Philips 400T/FEG microscope. Fig. 1 shows a typical bright field image of the 100% tetragonal(t) Zr02. The tetragonal structure was identified by both bulk x-ray diffraction and convergent beam electron diffraction (Fig. 2. A local region within a t-Zr02 grain was subjected to an intense electron beam irradiation which caused partial martensitic transformation of the t-Zr02 to monoclinic(m) symmetry, Fig. 3 A.

Analytical and High-Resolution EM Study of Crystalline Phases formed at Metal-Ceramic Interface

1990 ◽  
Vol 48 (2) ◽  
pp. 426-427
Author(s):  
N. Merk ◽  
A. P. Tomsia ◽  
G. Thomas
Keyword(s):  
Cross Section ◽  
Dissimilar Materials ◽  
Ceramic Materials ◽  
Electron Micrograph ◽  
Scanning Electron Micrograph ◽  
Structural Applications ◽  
Metal Ceramic ◽  
The Subject ◽  
Ceramic Compounds ◽  
Scanning Electron

A recent development of new ceramic materials for structural applications involves the joining of ceramic compounds to metals. Due to the wetting problem, an interlayer material (brazing alloy) is generally used to achieve the bonding. The nature of the interfaces between such dissimilar materials is the subject of intensive studies and is of utmost importance to obtain a controlled microstructure at the discontinuities to satisfy the demanding properties for engineering applications . The brazing alloy is generally ductile and hence, does not readily fracture. It must also wett the ceramic with similar thermal expansion coefficient to avoid large stresses at joints. In the present work we study mullite-molybdenum composites using a brazing alloy for the weldment.A scanning electron micrograph from the cross section of the joining sequence studied here is presented in Fig. 1.

Analytical Electron Microscopy of Surface-Modified Ceramics

1985 ◽  
Vol 43 ◽  
pp. 276-279
Author(s):  
P. S. Sklad
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Theoretical Models ◽  
Ceramic Materials ◽  
Solute Concentration ◽  
Second Phase ◽  
Analytical Electron ◽  
Implantation Techniques ◽  
Lattice Damage ◽  
Surface Modified

Over the past several years, it has become increasingly evident that materials for proposed advanced energy systems will be required to operate at high temperatures and in aggressive environments. These constraints make structural ceramics attractive materials for these systems. However it is well known that the condition of the specimen surface of ceramic materials is often critical in controlling properties such as fracture toughness, oxidation resistance, and wear resistance. Ion implantation techniques offer the potential of overcoming some of the surface related limitations.While the effects of implantation on surface sensitive properties may be measured indpendently, it is important to understand the microstructural evolution leading to these changes. Analytical electron microscopy provides a useful tool for characterizing the microstructures produced in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer, and annealing behavior. Such analyses allow correlations to be made with theoretical models, property measurements, and results of complimentary techniques.

Interface structures in polycrystalline ceramic materials

1986 ◽  
Vol 44 ◽  
pp. 468-471
Author(s):  
K. J. Morrissey
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Physical And Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Polycrystalline Materials ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

Probing vacancies and structural distortions at individual defects in ceramics using EELS

1996 ◽  
Vol 54 ◽  
pp. 678-679
Author(s):  
D. J. Wallis ◽  
N. D. Browning
Keyword(s):  
Structural Information ◽  
Core Loss ◽  
Nearest Neighbors ◽  
Ceramic Materials ◽  
Scanning Transmission Electron Microscope ◽  
Real Space ◽  
Atomic Scale ◽  
Structure Property ◽  
Scanning Transmission ◽  
Key Issues

In electron energy loss spectroscopy (EELS), the near-edge region of a core-loss edge contains information on high-order atomic correlations. These correlations give details of the 3-D atomic structure which can be elucidated using multiple-scattering (MS) theory. MS calculations use real space clusters making them ideal for use in low-symmetry systems such as defects and interfaces. When coupled with the atomic spatial resolution capabilities of the scanning transmission electron microscope (STEM), there therefore exists the ability to obtain 3-D structural information from individual atomic scale structures. For ceramic materials where the structure-property relationships are dominated by defects and interfaces, this methodology can provide unique information on key issues such as like-ion repulsion and the presence of vacancies, impurities and structural distortion.An example of the use of MS-theory is shown in fig 1, where an experimental oxygen K-edge from SrTiO3 is compared to full MS-calculations for successive shells (a shell consists of neighboring atoms, so that 1 shell includes only nearest neighbors, 2 shells includes first and second-nearest neighbors, and so on).

Conditions for atomic imaging of mullite

1989 ◽  
Vol 47 ◽  
pp. 418-419
Author(s):  
T. A. Epicier ◽  
G. Thomas
Keyword(s):  
Oxygen Vacancies ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Work Conditions ◽  
Real Space ◽  
Potential Candidate ◽  
Silicate Mineral ◽  
Resolution Electron ◽  
The Subject ◽  
Aluminium Silicate

Mullite is an aluminium-silicate mineral of current interest since it is a potential candidate for high temperature applications in the ceramic materials field.In the present work, conditions under which the structure of mullite can be optimally imaged by means of High Resolution Electron Microscopy (HREM) have been investigated. Special reference is made to the Atomic Resolution Microscope at Berkeley which allows real space information up to ≈ 0.17 nm to be directly transferred; numerous multislice calculations (conducted with the CEMPAS programs) as well as extensive experimental through-focus series taken from a commercial “3:2” mullite at 800 kV clearly show that a resolution of at least 0.19 nm is required if one wants to get a straightforward confirmation of atomic models of mullite, which is known to undergo non-stoichiometry associated with the presence of oxygen vacancies.Indeed the composition of mullite ranges from approximatively 3Al2O3-2SiO2 (referred here as 3:2-mullite) to 2Al2O3-1SiO2, and its structure is still the subject of refinements (see, for example, refs. 4, 5, 6).

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