Glossary
- Glas
- Ceramics
- Plastics
- Metals
- Finite Elements Method ( FEM )
- Brazilian Disk Test
- Refractories
- Technical Ceramics
Glas
Glas is the only material with inexhaustible raw materials. Its transformable and fascinates mankind for more than 2000 years with its rich colours and versatile applications. Once used as pure decorative material, glas became a constructive material during the last decades. Complex glas-ceramics -well known as Ceran© ceramic stove tops became part of daily live. In laboratory applications, glas has an outstanding chemical resistivity against acids, bases and organic solvants. The resistivity is higher than most plastics, combined with transparency and form Stability, even at higher temperatures.
In the field of architecture, glas is already used as a main constructive element. The basic machanical properties of glas are excellent: a compressive strength comparable to high strength steel, a tensile strength........, a youngs modulus and thermal expansion like aluminium. Presently, the glas industry develops new specifications for contruction in respect to this new importance of glas. The materials centre Rheinbach enables you to test your glass materials on physical and thermal properties. In addition, the corrosion behaviour may be tested
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Ceramics
Ceramic is the eldest material of mankind. Today, ceramic materials are irreplacable in modern technology. Due to their unique properties and combinations of properties, solutions with ceramic materials are convincing. Properties such as resistivity against abrasion and corrosion, thermal and electrical insulation, high temperature resistivity in combination with low densities make ceramics so unique.Technical ceramics are found in nozzels, valves and sensors in almost any device of every day use. Often, the user relies on ceramic components without even realizing, because they operate inside of larger components. Ceramic materials demand a cermic friendly construction to manifold the advantages of technical ceramics. The materials selection and the shape of each component is influenced by the conitions of use. Materials centre Rheinbach supports producer and operator during analysis and definition of demands and constructive prerequisites already during development.In addition to all standard testing methods, our team posseses comprehensive know-how and offers unique advantages to producers and operators of ceramics, ceramic compounds and refractory materials.
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Plastics
Plastics are the most popular materials in the world today. Its hard to mention any product without the implementation of plastics. Its application ranges from light weigthing packing material until high temperature resistant space material. Innovations allow always more and mew fields of application. At the same time, plastic materials contribute to efficieny, comfort, safety and environmental protection. In laboratories, plastic materials prevail beside glas. Breaking strength and low weight are the major advantage of plastics combined with strongly varying physical and chemical properties. Plastics, pricipally distinguished into elastomeres, duroplasts and thermoplasts help to reduce weight and save costs. Especially the combination of "light, heat resistandt and corrosion resistant" is oftenly demanded. Contact the materials centre Rheinbach for materials selction and testing. We test yield stress, tensile strength, fracture strength, youngs modulus, hardness acc. Shore and Rockwell, impact strength acc. Izod or Charpy and the thermal resistance of the shape.
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Metals
Although one of the oldest materials, especially metals show a potential that is uncomparable. For automotive industry, steel is the dominating material until today. With its recycling rate of nearly 100%, steel is very environment friendly. Steel is unsurpassed elastic and bears high loads without deformation. But also other metals such as aluminium and magnesium gain importance. Referring to their weigth, they even exceed steel in their strength. The lightest material is magnesium with 1,8g/cm3, with unlimited resources and good recyclability. Materials for light weigth constructions such as aluminium- which is 2/3 ligther than steel - replace more and more the " traditional material" steel, not only in automotive industry.
Especially the use of aluminium and megnesium requires detailed materials knowledge. Properties such as tensile strength at varying temperatures highlydepend on the alloy composition, often in the range of ppm. Here, the materials centre Rheinbach offers solutions to producers, processors and users by investigations of physical and chemical properties.
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Finite Elements Method ( FEM )
Due to the achieved progress in computer technology, computer based numeric calculation models for the evaluation of mechanical systems are established today. Even most complex constructions may be evaluated at a very early stage of development without any model
The principle of FEM is to fraction large geometries into small parts, the so called finite elements.These sinlge elements are connected by knots. By additional preselection of boundary conditions, the load parameters are detected ba y software. The software will then etsblish internally a complex equation system, including all preselected parameters.
The FEM calculation always consists of three processes:
First, an input of all informations referring to geometry and load is done into the preprocessor
Then, a solver algorithm solves the equation system basing on the input, which - depending on the complexity - may take several hours.
At the end, the results are processed to a graphic result output by the so called postprocessor, and are visualised e.g. by different colours.
The example shows the simulation of a brazilian disk test:
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Brazilian Disk Test -
Indirect testing of the tensile strength of ceramic parts.For the determination of materials, the determination of their strength - especially their tensile strength is of major importance. The direct testing of the tensile strength of brittle materials however is very complex.
At the moment, test set ups as the three point or four point bending tests prevail. Their disadvantage is the low part of volume that is actually charged with the load and the strong dependency of the samples surface and their dimension. AN attractive alternative to this is the indirect testing of tensile strength by the so called Brazilian Disk Test. This method is used for the testing of concrete since long times.
Opposite to those methods used for ceramics, the crack onset during the brazilian disk test is in the samples center and not at the edges. This leads to the special advantages, summarized as follows:
- simple sample geometry
- low effort, cost reduction
- small influence of the surface quality
- cost reduction, time reduction
- small samples
- more samples per volume; testing of fragments possible
- large effectively loaded volume
- low variation
- higher precision of the single values, required number of sampes is lower, higher reproducibility of the measured values.
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Refractories
Refractories are used for the lining of high temperature plants. Under mechanical load they shall not suffer from a loss of shape, must be stable under application conditions und have to resist sudden temperature changes without any loss of physical stability. Technological testings at room temperature, as they are done at the Materials Center Rheinbach are done to assure quality control. These testings mainly are the determination of porosity, cold bending strength, compression strength and investigation of a refractories structure in the Scanning Electron Microscope.
Thermal testings however give additional information about the materials under application conditions. These are e.g. investigations of hot abrasion testing, hot bending strength or testings for the thermal shock resistance.
At the Materials Center Rheinbach a method for the investigation of hot abrasion resistance was developed according to ASTM 704-88. This method allows getting information about a materials ability to resist abrasive wear under a certain application temperature. SiC particles are used as abrasives, which are blasted onto the sample under well defined conditions.
The hot bending strength his measured in a customized plant, allowing to establish temperatures up to 1600C and to measure the hot bending strength by the three point measuring method. With an additional displacement transducer, the Youngs Modulus may be quantified.
At the Materials Center Rheinbach, the thermal shock resistance of both oxidic and non oxidic refractories is measured. The investigation of graphite containing refractories plays a special role, because these samples are heated up in customized furnaces in an inert gas atmosphere. According to the selected method, crack propagation or the remaining bending strength acc. Hasselman or thermal fatigue may be assessed.
Technical Ceramics
The expression " Technical Ceramics" comprises all ceramic materials, used for technical applications. This includes all application from functional ceramics, construction ceramics until to refractories.
The technical use of ceramic materials began with refractories. For the production of glass pots, special clays were necessary with a high softening point. The clays of Großalmerode had their monopoly in the 16th and 17th Century for this application.
For higher temperatures, needed in metallurgical applications, graphite crucibles were used, produced in the areas around Passau since the middle age. A graphite concentrate was produced of graphite shales located east of Passau. Together with potters clay, a highly thermal shock resistant and acid resistant black pottery was produced. These met the middle age demands on metallurgical melting processes.
The opening of deposits of Ceylon - today Sri Lanka - by the British in the 19th Century caused the availability of better materials in Europe and is the reason for Great Britains important role in the production of graphite crucibles during that time. The development of refractories was mainly controlled by the demands of the steel industry. During a fast sequence, fireclay products were improved and new materials such as silica-magnesia and Doloma bricks were developed. Due to the recovery of a magnesia deposit in the Steiermark, Austria, the development of basic refractories was influenced worldwide. Since the end of the 19th Century, many other refractories were developed
New demands on ceramic materials came up, when Werner von Siemens used porcelain insulators for the telegraph conductor from Frankfurt to Berlin in 1849. At that time, porcelain only could be used as insulation material, which in addition resisted climate influence and change. Therefore, the research on porcelain materials began, focusing on an improvement of the structure and thereby improving porcelains properties.
During the emerging motorisation ceramics were irreplaceable e.g. for spark plugs. The production of spark plugs marked an important milestone in the history of ceramics. With the increase of motorisation and more powerful engines, the initial insulation material of the first electrical spark plugs showed up to be insufficient. Antiknock additives were found in the form auf carbonyl iron. This however led to oxidation of the porcelain - and later - steatite isolators. Aluminium oxide, produced by the between 1887 and 192 developed "Bayer" process was an alternative raw material. In 1931, Siemens&Hanke succeeded in the production of a spark plug made of sintered alumina. For the first time, a synthetic raw material was used for the production of ceramics. Today, the use of synthetic raw materials for technical ceramics is common.
The breakthrough of ceramic materials out of the traditional applications began in the 50ies of the 20th century. Improvements in the fields of processing and analytics supported the development of new applications. Special impulses were released by reactor technologies and aerospace technology.
During the 70ies, functional ceramics had a breakthrough. This includes especially materials, used for electronics and electro technology. Until today, functional ceramics have a share of 80% of all technically used ceramics. IN the same times, silicon nitride was developed, opening completely new fields of application. In the 80ies, a ceramic euphoria was released. Especially under the key words of " ceramic engine" and "automobile gas turbine" many research activities were started. However, the high expectations could not be fulfilled during that short time. By the development of ceramic superconductors, the euphoria was even increased, followed by a disillusion in the 90ies.
Today, technical ceramics is equal to other materials and often is found in the fields of high tech applications. Many research results of the past decades are not yet converted into production, this offers a large potential. This industrial branch in Germany produced in the 90ies goods of a value of 1,5 Billion Euro with 12000 employees. The world market for technical ceramics is evaluated by the "Verband der Keramischen Industrie" to more than 10 Billion Euro, which is roundabout 15% of the total ceramic market. The production index for technical ceramics in Germany gained 25% between 1991 and 1998.
Source: "Technische Keramik", W. Kollenberg (Hrsg.), Vulkan-Verlag Essen, 2004
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Technical CeramicsThe expression " Technical Ceramics" comprises all ceramic materials, used for technical applications. This includes all application from functional ceramics, construction ceramics until to refractories.
The technical use of ceramic materials began with refractories. For the production of glass pots, special clays were necessary with a high softening point. The clays of Großalmerode had their monopoly in the 16th and 17th Century for this application.
For higher temperatures, needed in metallurgical applications, graphite crucibles were used, produced in the areas around Passau since the middle age. A graphite concentrate was produced of graphite shales located east of Passau. Together with potters clay, a highly thermal shock resistant and acid resistant black pottery was produced. These met the middle age demands on metallurgical melting processes.
The opening of deposits of Ceylon - today Sri Lanka - by the British in the 19th Century caused the availability of better materials in Europe and is the reason for Great Britains important role in the production of graphite crucibles during that time. The development of refractories was mainly controlled by the demands of the steel industry. During a fast sequence, fireclay products were improved and new materials such as silica-magnesia and Doloma bricks were developed. Due to the recovery of a magnesia deposit in the Steiermark, Austria, the development of basic refractories was influenced worldwide. Since the end of the 19th Century, many other refractories were developed
New demands on ceramic materials came up, when Werner von Siemens used porcelain insulators for the telegraph conductor from Frankfurt to Berlin in 1849. At that time, porcelain only could be used as insulation material, which in addition resisted climate influence and change. Therefore, the research on porcelain materials began, focusing on an improvement of the structure and thereby improving porcelains properties.
During the emerging motorisation ceramics were irreplaceable e.g. for spark plugs. The production of spark plugs marked an important milestone in the history of ceramics. With the increase of motorisation and more powerful engines, the initial insulation material of the first electrical spark plugs showed up to be insufficient. Antiknock additives were found in the form auf carbonyl iron. This however led to oxidation of the porcelain - and later - steatite isolators. Aluminium oxide, produced by the between 1887 and 192 developed "Bayer" process was an alternative raw material. In 1931, Siemens&Hanke succeeded in the production of a spark plug made of sintered alumina. For the first time, a synthetic raw material was used for the production of ceramics. Today, the use of synthetic raw materials for technical ceramics is common.
The breakthrough of ceramic materials out of the traditional applications began in the 50ies of the 20th century. Improvements in the fields of processing and analytics supported the development of new applications. Special impulses were released by reactor technologies and aerospace technology.
During the 70ies, functional ceramics had a breakthrough. This includes especially materials, used for electronics and electro technology. Until today, functional ceramics have a share of 80% of all technically used ceramics. IN the same times, silicon nitride was developed, opening completely new fields of application. In the 80ies, a ceramic euphoria was released. Especially under the key words of " ceramic engine" and "automobile gas turbine" many research activities were started. However, the high expectations could not be fulfilled during that short time. By the development of ceramic superconductors, the euphoria was even increased, followed by a disillusion in the 90ies.
Today, technical ceramics is equal to other materials and often is found in the fields of high tech applications. Many research results of the past decades are not yet converted into production, this offers a large potential. This industrial branch in Germany produced in the 90ies goods of a value of 1,5 Billion Euro with 12000 employees. The world market for technical ceramics is evaluated by the "Verband der Keramischen Industrie" to more than 10 Billion Euro, which is roundabout 15% of the total ceramic market. The production index for technical ceramics in Germany gained 25% between 1991 and 1998.
Source: "Technische Keramik", W. Kollenberg (Hrsg.), Vulkan-Verlag Essen, 2004
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