- Chemical Properties Definition: Chemical properties involve how materials react chemically when they contact other substances, affecting their integrity and function.
- Physical Properties of Materials: Understanding the physical properties helps in assessing material behavior under mechanical stresses and environmental conditions.
- Atomic Bonding Impact: Atomic bonding determines key material characteristics such as melting point and electrical conductivity.
- Corrosion Resistance: A material’s ability to withstand environmental degradation without losing strength, primarily through its composition and treatment.
- Acidity and Alkalinity: The pH value of a material indicates its acidity or alkalinity, which affects how it interacts with other materials.
For engineers, understanding the chemical properties of materials is crucial. These properties dictate how materials react when they come into contact with others, potentially leading to deterioration. Below are some key chemical properties of engineering materials:
- Chemical composition
- Atomic bonding
- Corrosion resistance
- Acidity or Alkalinity
Chemical Composition
The chemical composition of engineering material indicates the elements which are combined together to form that material. Chemical composition of a material effects the properties of engineering materials very much. The strength, hardness, ductility, brittleness, corrosion resistance, weldability etc. depends on chemical composition of materials.
Hence, we should also have the knowledge of chemical composition of engineering materials. For Example the Chemical compositions of some materials are listed below-
| Sl. No. | Material | Chemical Composition |
| 1. | Steel | Fe, Cr, Ni |
| 2. | Brass | Cu = 90%, Ni = 10% |
| 3. | Bronze | 90% Cu, 10% Ni |
| 4. | Invar | Fe = 64%, Ni = 36% |
| 5. | Gun Metal | Cu = 88%, Tin = 10%, Zn = 2% |
| 6. | German Silver or Nickel Silver or Electrum | Cu = 50%, Zn = 30%, Ni = 20% |
| 7. | Nichrome | Ni = 60%, Cr = 15%, Fe = 25% |
| 8. | Phosphor Bronge | Cu = 89 – 95.50% , Tin = 3.50 -10%, P = 1% |
| 9. | Manganin | Cu = 84%, Mn = 12%, Ni = 4% |
| 10. | Constantan | Cu = 60%, Ni = 40% |
Atomic Bonding
Atomic bonding defines how atoms are linked to form a material, influencing its melting point, boiling point, and electrical conductivity. Understanding these bonds is essential for mastering material properties:
- Ionic bond – froms by exchanging of valence electrons between atoms.
- Covalent bonds – froms by sharing of electrons between atoms.
- Metallic bonds – found in metals.
Corrosion Resistance
Corrosion is the chemical or electrochemical degradation of metals by their environment, transforming them into oxides, salts, or other compounds. Influenced by air, industrial environments, and chemicals, corrosion significantly reduces a material’s strength and lifespan.
Corrosion resistance of a material is the ability of material to resist the oxidation in atmospheric condition. Generally pure metals such as iron, copper, aluminum etc. gets corroded in slowly in atmosphere. To avoid the corrosion of these metal in pure form, we use these metals in the form of alloys such as stainless steel, brass, bronze, German silver, Gunmetal etc.
Acidity or Alkalinity
The acidity or alkalinity of engineering materials, determined by their pH value, is a crucial chemical property. pH values range from 0 to 14, with 7 being neutral (like ordinary water). Materials with a pH below 7 are acidic, while those above 7 are alkaline, influencing their reactions with other materials.
