부식 및 소재 선택: 합금, 고분자 및 복합재료
도입됨
어휘
| English | 의미 |
|---|---|
| corrosion/kəˈrəʊʒn/ | 부식 |
| alloy/ˈælɔɪ/ | 합금 |
| composite/ˈkɒmpəzɪt/ | 복합재료 |
| sacrificial protection/ˌsækrɪˈfɪʃl prəˈtekʃn/ | 양극 보호 |
| carat | 캐럿 |
| thermosoftening polymer | 열가소성 고분자 |
| thermosetting polymer/ˈθɜːməsɪtɪŋ ˈpɒlɪmə/ | 열경성 고분자 |
| matrix/ˈmeɪtrɪks/ | 매트릭스 |
| reinforcement/ˌriːɪnˈfɔːsmənt/ | 보강재 |
English
Why can two coatings fail differently?
- Paint and zinc can both separate iron from its environment. After a scratch, their protection can differ because zinc can react in place of the iron.
- This lesson covers Separate Chemistry materials: corrosion 腐蚀, alloys 合金, ceramics, polymers and composites 复合材料. Choose a material by the properties needed for its job, using the actual supplied data.
English
Test what rusting needs
- Corrosion is destruction by chemical reactions with the environment. Iron rusts when both water and oxygen are available. Compare equivalent nails over the same time and temperature.
- Damp air supplies both; dry air with drying agent removes water; boiled water under oil limits oxygen. Keep the last nail fully submerged. The controls distinguish two necessary conditions rather than proving a rule from one rusty nail.
English
Compare barriers with sacrificial protection 牺牲保护
- Paint, grease and suitable electroplating make barriers. A scratch exposes iron to water and oxygen. Zinc galvanising also provides sacrificial protection because zinc is more reactive than iron and oxidises preferentially.
- Nearby exposed iron can remain protected while suitable zinc contact and supply remain. A less reactive coating cannot provide the same sacrifice. Aluminium's adherent oxide layer protects its surface; this does not mean aluminium never reacts.
연습
스크래치 부위 근처의 철을 아연이 보호할 수 있는 이유는 무엇입니까?
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
아연은 철보다 반응성이 커서 제물 보호를 제공하며, 적절한 접촉과 아연 공급이 유지됩니다. 반응성이 낮은 코팅은 해당 장벽 보호만 제공합니다.
English
Match each alloy to its purpose
- Bronze contains copper and tin; brass contains copper and zinc. Gold jewellery can contain silver, copper or zinc to improve hardness and wear. Different atom sizes can hinder sliding of regular metal layers.
- High-carbon steel is strong/hard but brittle; low-carbon steel is softer and easier to shape; stainless steel contains chromium and nickel and resists corrosion. Aluminium alloys have low density useful for aircraft. Use unfamiliar alloy data rather than assuming every alloy is best at everything.
English
Interpret carats 开 as a mass fraction
- Pure gold is 24 carat. Eighteen carat means a gold mass fraction $18/24=0.75$, or $75\%$, rather than eighteen percent.
- A 12 g ring contains $m_{gold}=12\times18/24=9$ g of gold and $12-9=3$ g of other metals. An independent 8 g ring of the same purity contains 6 g of gold; the fraction stays the same when total mass changes.
연습
8 g 반지는 18 카arat 금입니다. 금의 질량을 계산하십시오.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
금 질량 = 총 질량 × 금 분율 = 8 g × 18/24 = 6 g. 18카arat는 75%의 금이며, 18%가 아닙니다. 남은 2 g은 다른 금속입니다.
English
Make glass and clay ceramics
- Soda-lime glass is made from sand, sodium carbonate and limestone. Borosilicate glass uses sand and boron trioxide and has a higher melting temperature.
- Clay ceramics such as bricks and pottery are made by shaping wet clay and heating it in a furnace. Hardness, brittleness and heat resistance affect suitability; the highest strength alone does not establish the best material for impact.
English
Distinguish polymer packing from cross-linking
- Low-density and high-density poly(ethene) use the same ethene monomer. Different production conditions lead to branching/packing differences: branched chains pack less closely than straighter chains.
- A thermosoftening polymer 热塑性聚合物 has separate chains that can move when heated as intermolecular attractions are overcome. A thermosetting polymer 热固性聚合物 has covalent cross-links forming a network and does not melt; strong heating can decompose it. Melting separate chains does not break their covalent backbone.
연습
열소성 고분자를 녹이는 것은 공유 결합 사슬 골격을 끊어야 합니다.
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
가열로 분자 간 인력을 충분히 극복하여 개별 사슬이 이동할 수 있게 됩니다. 공유 결합 골격을 끊는 것이 녹는 과정이 아닙니다. 공유 결합 교차결합은 열소성 네트워크가 녹지 않도록 저항하게 하며, 강한 가열로는 분해시킬 수 있습니다.
연습
용어를 정확한 의미와 매칭하십시오.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
용어를 구분하기 위해 화학 구조, 공정 또는 비교 경계를 사용하십시오.
English
Choose a composite with an explicit limit
- A composite has a matrix 基体 surrounding and binding a reinforcement 增强体 of fibres or fragments: glass fibres in resin, carbon fibres in polymer resin, or aggregate in a cement-based binder. Name both components; “carbon fibre” alone is incomplete.
- Fictional candidates have density/strength values A: 7.8/500, B fibre-resin: 1.6/600, C ceramic: 2.4/650 with brittleness, in common supplied units. B is promising for a light impact-resistant part, but impact tests, temperature, cost and service lifetime are still needed. Do not invent certainty from one number.
Key idea
Match structure or reaction to the property, then the property to the use. State a condition or missing measurement that limits the recommendation.
연습
재료 증거를 올바르게 사용한 두 가지 결론은 무엇입니까?
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
특성은 서비스 요구사항과 일치해야 합니다. 사슬 분지/포장은 생산 조건에 의존하며, 알루미늄의 보호 산화막 자체도 반응产物입니다. 최대 강도만으로 충격 거동을 결정할 수 없습니다.
연습
섬유 보강 복합재의 외부 바인더는 무엇이라고 합니까?
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
매트릭스는 보강재를 감싸고 결합합니다. 유리섬유/수지 composite에서는 수지가 매트릭스이고 유리섬유가 보강재입니다.