Enhancement of materials：練習問題

A manufacturer is producing a batch of outdoor garden furniture made from a specific softwood. Which of the following enhancement methods would be most effective for ensuring the timber resists fungal attack and decay when in constant contact with the ground?

In the heat treatment of a high-carbon steel tool, the material is heated to a critical temperature and then rapidly quenched. Why must the material then undergo tempering?

A designer is developing a specialized medical casing that must be biodegradable but also requires specific mechanical stiffness. They are considering Polyactide (PLA). Which enhancement or characteristic of PLA would be a critical limitation if the product were exposed to temperatures exceeding \(60^{\circ}C\)?

In the enhancement of metals, what is the primary purpose of the tempering process after a steel component has been hardened?

A structural component in a marine environment requires case hardening. Which of the following best describes the material requirement and the resulting enhancement?

Compare the use of case hardening and hardening and tempering in terms of the resulting material properties of a low carbon steel component.

Explain how the addition of UV stabilisers enhances the performance and longevity of a polymer-based product intended for permanent outdoor use, such as garden furniture.

A high-performance mountain bike frame is being designed for professional racing. The designer has opted for 6061-T6 Duralumin (an aluminium alloy) for the main tubes.

(a) Justify the choice of a non-ferrous alloy like Duralumin over low carbon steel, with reference to two specific mechanical properties.
(b) The frame undergoes a heat treatment process to reach the 'T6' temper. Explain the hardening and tempering process and how it modifies the internal structure of the metal to improve performance.