Makalah Tungsten | Tungsten | Melting Point

TUNGSTEN Wolfram is a chemical element in the periodic table that has the symbol W and atomic number 74. The name of the element is taken from the latin Wolframium and is often called Tungsten. Very hard transition metal and gray to white is found in minerals like wolframite and schelit. Tungsten has a melting point higher than nonalloy other substances. Wolframe pure form is used mainly in electronic devices. Its coumpounds and alloys are widely used for many things, most notably as a light bulb filament, x-ray tube, and superalloys.

 Structure Of Tungsten 1. Sub Atomic :  74 Protons (+), 74 electrons (-), 110 neutrons (0)  Has 6 energy level  Atomic Mass 183.84 amu (atomic mass unit)

2. Atom :

Structure, Properties, Process and Application of Tungsten

Hexagonal Close Packed

Tungsten crystal structure is Body centered Cubic, BCC is a basis type of cubic crystal structure. In crystallography, the cubic crystals structure is a crystal system where the unit cell has a cube shaped structure. This is one of the simplest crystal structure found in crystal metal. All these atomic properties of tungsten are related to its atomic structure. 3. Microschopic This is picture of Tungsten structure when viewed under a microscope (200 nanometer).

4.

Bulk

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Properti es Of

Tungsten 1. Mechanical Properties

Structure, Properties, Process and Application of Tungsten

Density of Tungsten is an important parameter among its mechanical properties. Tungsten density is nothis but exact value of its mass (weight) per unit volume. Its density at room temperature is 19.25 g/cm³. And if you talk about its density at liquid state, it is 17.60 g/cm³. Viscosity of Tungsten cannot be determined, as the concept of viscosity is only applicable to fluid (liquid state) substances. Tensile strength of tungsten is 370.00 Mpa. Its tensile strength reflects the effect of applied force to wrench the metal while it reaches the point where it breaks down into pieces. The elasticity modulus of tungsten with respect to shear modulus, bulk modulus, and young’s modulus is 161.00 Gpa, 310.00 Gpa, and 411.00 Gpa. The value for poisson ratio of tungsten element is 0.28. All these values indicate the effect of the various stresses on the deformation amount of metal. This metal is ductile, malleable in nature. 2. Physical Properties Tungsten physical properties are one of the most important properties of this metal. The melting point is a fundamental parameter that constitutes the physical properties of tungsten. Melting point of tungsten is the temperature at which it changes from its solid state to a liquid state, at constant atmospheric conditions. Generally, the term ‘melting point’ and ‘freezing point’ are used interchangeably, depending on the state change. Tungsten’s melting point is 3,410.00 ˚C and tungsten boiling point is 5,660.00 ˚C. Tungsten melting point and its boiling point are two very prominent aspects of its physical properties, speed of sound of tungsten is 4,620.00 m/s. 3. Electrical Properties Choice of any metal for an electrical application is influenced by its electrical characteristics, the electrical property of tungsten metal is superconductor. Under certain conditions, superconductor metals offer zero ressistance to electric current it means this type of metals will conduct electricity without any resistance. The resistivity of tungsten defines its ability to resist the flow of electric current and its value is 52.80 nὨ.m

The electrical conductivity of tungsten (W) is 0.19 10 6/cm Ὠ. Its electrical conductivity explicates its ability to conduct electric current. The value for electron affinity of Tungsten element is 78.60 kJ/mol. While comparing the electrical properties of tungsten with others, electric conductivity and resisvity are the major deciding factors. Structure, Properties, Process and Application of Tungsten

4. Optical Properties Optical properties and hardness of Tungsten (W) include phenomenon such as refractive index, reflectivity, different hardness scales. Refractive index of tungsten is not available and its reflectivity is 62.00 %. Hardness of tungsten is ability to resist compression force applied externally. Hardness of tungsten metal according to Mohs Hardness, Brinell Hardness and Vickers Hardness is 7.50 Mohs, 341 HB, and 352 HV respectively. All these characteristics of tungsten are also called as the physical properties of tungsten. 5. Thermal Properties The enthalpy of tungsten has some variants like enthalphy of vaporization, fusion and atomization. Their values are enthalphy of vaporization 799.10 kJ/mol, enthalphy of fusion 35.23 kJ/mol, and 837.00 kJ/mol respectively. The specific heat of tungsten is 0.13 J/(kg.K). When the specific amount of heat is applied to this metal,some structural and behaviroal changes occur and those changes are known as the thermal properties of tungsten metal. Molar heat capacity tungsten is 24.27 J/mol.K . The critical temperature is the temperature at and above which the vapor of the metal cannot be liquified, no matter after how much extra pressure is applied on it. But the value for tungsten critical temperature is 0.13 J/(kg. K) The thermal conductivity og tungsten is 173.00 W/m.K. Its thermal conductivity is an ability of this metal to conduct heat. The thermal expansion of tungsten is 4.50 nanometer/(m.K). all these thermal properties of tungsten are related to the change in temperature or effect of heat and have a considerable impact on magnetic properties of tungsten. 6. Chemical Properties Tungsten metal has its characteristic behavior in chemistry which is defined by its chemical properties. Tungsten chemical properties definite its chemical formula, isotopes, oxides, electronegativity, ionization potential,etc. There are some other chemichal properties of tungsten such as ionization, radioactive isotopes, solubility which also play a significant role. Tungsten isotopes are its variants in which the number of neutrons present in the nucleus varies. Thus, the atomic number remains constant, but atomic mass varies with respect to atomic structure of tungsten. There are known isotopes of this metal. 

Process Of Tungsten

Structure, Properties, Process and Application of Tungsten

How cemented carbide is made : First, mix tungsten carbide with cobalt to make powder which can be classfied as raw materials. The granulated mixture is poured into a die cavity and pressed. It gives a moderate strength like that of chalk. Next, the pressed compacts are placed in a sintering furnance and heated at a temperature of about 1400˚C, resulting in cemented carbide.

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Application Of Tungsten

 In daily life : 1. Lamp filament Tungsten has the highest melting point so it was chosen as the filament lamp.

Structure, Properties, Process and Application of Tungsten

2. Ring from tungsten

 In fabrication : 1. Tungsten carbid dill bits

Structure, Properties, Process and Application of Tungsten

2. Eye chisel milling machine

Structure, Properties, Process and Application of Tungsten