The question of whether diamond is stronger than tungsten is common, but it cannot be answered simply. The public often uses “stronger” as a blanket description for durability, but in material science, this word is imprecise. Materials excel in different ways; one might be superior for cutting while another is better for resisting a heavy impact. To accurately compare diamond and tungsten, it is necessary to separate the concepts of hardness, strength, and toughness.
Understanding Material Properties
The properties that define a material’s performance under stress are distinctly categorized. Hardness is the measure of a material’s resistance to localized permanent deformation, such as scratching or indentation. This characteristic is often quantified using the Mohs scale, which ranks materials from 1 (softest) to 10 (hardest). A material’s tensile strength, conversely, describes its resistance to being pulled apart or stretched before it breaks.
The third property, toughness, measures a material’s ability to absorb energy and deform plastically without fracturing. A material that is tough will bend or dent under impact, whereas a hard material with low toughness is more likely to shatter. Judging which material is truly “stronger” depends entirely on whether resistance to scratching, stretching, or impact is being measured.
The Characteristics of Diamond
Diamond is a solid form of carbon where each atom is bonded to four neighbors in a rigid, three-dimensional tetrahedral lattice. This network of exceptionally strong covalent bonds is the source of its mechanical properties. Diamond is the hardest known natural substance, registering a perfect 10 on the Mohs scale. This supreme hardness makes it the ultimate material for cutting, grinding, and polishing other materials.
Despite its unmatched resistance to scratching, this highly ordered atomic structure makes diamond inherently brittle. While diamond resists surface wear, it has relatively low fracture toughness. A sharp, localized impact, like a hammer blow, can easily cause a diamond to cleave or shatter along its planes of atomic weakness. This trade-off explains why diamond is used for fine cutting edges but not for structural applications requiring resilience to sudden shock.
The Characteristics of Tungsten
Tungsten is a pure metal known for having the highest melting point of any metal, at 3,422°C, and an extremely high density. However, in most industrial comparisons with diamond, the material referenced is Tungsten Carbide (WC), a compound formed by tungsten and carbon atoms. Tungsten Carbide typically ranks between 9 and 9.5 on the Mohs scale, making it nearly as hard as diamond and significantly harder than pure tungsten.
Tungsten Carbide is primarily utilized in a form called cemented carbide, where the hard WC particles are embedded in a tough metal binder, often cobalt. This combination grants the material immense compressive strength and high fracture toughness. Unlike pure diamond, this cemented composite structure allows Tungsten Carbide to absorb substantial impact energy without shattering. Its ability to maintain structural integrity under heavy loads and high wear makes it a versatile choice for extreme applications.
Answering the Core Question: Which is “Stronger”?
Diamond is definitively the harder material, and nothing currently used in industry can scratch it. This makes it the superior choice for any application where maximum surface abrasion resistance or a razor-sharp cutting edge is necessary, such as specialized micro-drills or industrial abrasive powders. However, in terms of practical strength and toughness, Tungsten Carbide is the superior engineering material.
Tungsten Carbide excels in structural integrity, especially its resistance to failure under compressive force, which can be up to 7,000 megapascals. This high toughness means that while a diamond cutter might chip or shatter when dropped, a Tungsten Carbide drill bit or armor-piercing round can withstand tremendous impact and stress without failing. If “stronger” means resistance to being pulled apart (high tensile strength) or resistance to catastrophic failure from impact (high toughness), then Tungsten Carbide holds the advantage. The choice depends on the intended use: diamond for unparalleled surface hardness and cutting, and Tungsten Carbide for structural durability and impact resistance.