Domanda del libro di testo
Describe the reactions that occur when an Si1OH24 sol
becomes a gel. What is the formula of the ceramic obtained
when the gel is dried and sintered?
312
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Ch.12 - Solids and Solid-State Materials
McMurry8th EditionChemistryISBN: 9781292336145
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TOC.tableOfContents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
Capitolo 12, Problema 133
Explain why silicon carbide–reinforced alumina is stronger and tougher than pure alumina.
Guida verificata passo dopo passo1
1. Silicon carbide (SiC) is a very hard substance and can serve as a reinforcement added to alumina to improve the composite's mechanical properties. When SiC is mixed with alumina, it forms a composite material that is stronger and tougher than pure alumina.
2. The addition of SiC to alumina creates a material with a more complex microstructure. This microstructure can help to stop the propagation of cracks, which is a common cause of failure in brittle materials like alumina. When a crack starts to form in the composite material, it is likely to hit a SiC particle and be deflected or stopped, reducing the likelihood of catastrophic failure.
3. The SiC particles also help to distribute the applied stress over a larger area, reducing the local stress and making the material more resistant to deformation and failure.
4. The SiC particles can also create a toughening mechanism known as 'crack bridging'. In this process, the SiC particles act as bridges across the crack, holding the crack faces together and preventing the crack from growing.
5. Therefore, the addition of SiC to alumina results in a composite material that is stronger and tougher than pure alumina due to the complex microstructure, crack deflection, stress distribution, and crack bridging.
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Composite Materials
Composite materials are made from two or more constituent materials with significantly different physical or chemical properties. In the case of silicon carbide-reinforced alumina, the combination enhances mechanical properties such as strength and toughness. The reinforcement helps to distribute stress more evenly, preventing failure and improving overall performance.
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Percorso guidato
08:12
Laboratory Materials 2
Mechanical Properties: Strength and Toughness
Strength refers to a material's ability to withstand an applied load without failure, while toughness is the ability to absorb energy and deform plastically without fracturing. Silicon carbide, being a hard and strong material, contributes to the overall strength of the composite, while its ability to inhibit crack propagation enhances toughness, making the composite more resilient than pure alumina.
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03:06Reaction Mechanism Overview
Crack Propagation and Fracture Mechanics
Fracture mechanics studies how cracks propagate in materials and how they can be prevented. In silicon carbide-reinforced alumina, the presence of silicon carbide can impede crack growth by bridging cracks and redistributing stress. This mechanism not only increases the toughness of the material but also enhances its durability under mechanical stress compared to pure alumina.
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Percorso guidato
03:06Reaction Mechanism Overview
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Silicon nitride 1Si3N42, a high-temperature ceramic useful
for making engine components, is a covalent network solid
in which each Si atom is bonded to four N atoms and each
N atom is bonded to three Si atoms. Explain why silicon
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834
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Domanda del libro di testo
A group 3A metal has a density of 2.70 g/cm3 and a cubic unit cell with an edge length of 404 pm. Reaction of A 1.07 cm3 chunk of the metal with an excess of hydrochloric acid gives a colorless gas that occupies 4.00 L at 23.0 °C and a pressure of 740 mm Hg. (a) Identify the metal.
356
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Domanda del libro di testo
Explain why graphite/epoxy composites are good materials
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335
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Domanda del libro di testo
A cube-shaped crystal of an alkali metal, 1.62 mm on an edge, was vaporized in a 500.0 mL evacuated flask. The resulting vapor pressure was 12.5 mm Hg at 802 °C. The structure of the solid metal is known to be body-centered cubic. (b) Use the data in Figure 5.19 to identify the alkali metal.
645
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