What is materials science?
It is an interdisciplinary science that studies the relationship between composition, structure, manufacturing technologies, processing, and properties of materials. The sciences involved in the research are mainly physics, chemistry, and mathematics. Typically, the subject of research is solid materials, followed by liquids and gases. The properties studied include structure, electrical, magnetic, thermal, optical, mechanical properties, or combinations of these properties with the aim of creating materials to meet engineering needs.
Materials research creates countless applications in life, which is why the fields of materials science and materials technology are becoming increasingly popular and widely developed.
Material classification
Materials are the subject of the field of materials science, consisting of many different types based on material nature, material structure, and properties,... Typically, if classified by material nature, we have the following types:
1. Metal materials
Metal materials are currently divided into two types: ferrous metal materials and non-ferrous metal materials.
Black metal materials include cast iron, steel, and their alloys (mostly containing iron). These are alloys based on iron and carbon. The carbon content is assessed by weight percentage. If there is 1 kg of carbon in 100 kg of steel, then the carbon content is 1%. When the carbon content is more than 2.14%, we have cast iron; if less than 2.14%, we have steel.
- Steel includes carbon steel and alloy steel. In fact, carbon steel does not mean that the composition is only entirely iron and carbon. In the iron metal matrix, besides carbon (< 2.14%), there are also common impurities such as Mn, Si, S, P, and random impurities like Cr, Ni, Cu, W, Ti, Mo... When the content of these substances exceeds a certain value, the steel will be considered alloy steel.
Carbon steel: In carbon steel, besides iron, attention is paid to adjusting the composition of the elements: C (<2%), Mn (0.5-0.8%), Si (0.3-0.6%), P (0.05-0.06%), S (0.05-0.06%).
Phosphorus and sulfur are the two enemies of all types of steel. The quality of steel, whether high or low, is sometimes assessed by the content of residual phosphorus and sulfur in the composition. High-quality steel is steel that does not contain more than 0.025% of each of the above elements. Phosphorus is present in steel from ore or from coal, existing in steel in a form dissolved in ferrite or bonded with iron as Fe3P, making the steel brittle when cold, known as cold brittleness or cold fragility. Sulfur is also present in steel from ore or from coal.
The eutectic mixture (FeS + Fe) has a lower melting point than cast iron and is located at the grain boundaries; when heated for pressure processing, this eutectic phase melts, causing the steel to break at the grain boundaries, giving a feeling of brittleness; this phenomenon is called hot brittleness or hot fragility.
Mn and Si are added to deoxidize while still in the molten metal during smelting, where the deoxidizing effect of silicon is stronger. These two elements, when present in iron, also increase strength and hardness, but their effect on reducing ductility and toughness is very strong, so they are only used in limited amounts.
Steel used for common structures in the construction industry (plates, bars, wires, pipes, U-shaped steel, I-shaped steel...) is low-quality carbon steel, with phosphorus and sulfur below 0.06%.
Structural steel (steel used for common machine parts) has higher quality, S < 0.04%, P < 0.035%. This steel is always deoxidized with both manganese and silicon. The strength of the steel increases as the carbon content increases; however, do not use a carbon content higher than 0.85% because the strength from that point onward will not increase but will decrease. Structural steel with a carbon content of 0.85% can withstand a tensile strength of 1150 MPa, meaning that if a steel wire made of this steel with a cross-section of 1 mm² can support a weight of 115 kg.
Rail steel is steel with 0.5-0.8% carbon; 0.6-1% manganese; phosphorus, sulfur < 0.04%, usually has its own manufacturing plant. The tensile strength of the wire depends on both the amount of carbon and the degree of deformation when drawn (during production), typically the carbon content does not exceed 1.2%, the tensile strength limit can be very high, for example, produced from 1.2% carbon steel, cold drawn to a deformation level of 90%, the wire has a strength limit of 4000 MPa meaning that a wire with a cross-section of 1 mm² can support 400 kg.
Alloy steel is steel (with the main components being iron and carbon) that is melted and mixed with other chemical elements (copper, manganese, nickel,...) with a total amount of added elements ranging from 1.0% to 50% of the total mass of the mixture to improve the quality of the finished steel. Depending on the different quantities of the elements and their ratios in the steel, the hardness, elasticity, ductility, strength, and oxidation resistance of the finished steel can change.
In Russia, China, and some Eastern countries, alloy steel is divided into three groups: low alloy steel, medium alloy steel, and high alloy steel. In the West, only two types are distinguished: low and high. The difference between these two types does not have a clear boundary. According to Russian standards, low alloy steel has a total alloy content of less than 2.5%, while in high alloy steel, this ratio is greater than 10%. Generally, the term "alloy steel" is used to refer to low alloy steel.
Non-ferrous metals are easy to stretch, easy to thin, have wear resistance, high corrosion resistance, and most have good thermal and electrical conductivity. Non-ferrous metals are less oxidized in the environment. The main non-ferrous metals are copper (Cu), aluminum (Al), and their alloys.
- Silicate materials
- Ceramic materials
The ceramic materials mentioned in this article are primarily chemicals in oxide form, used in the ceramics industry. They can be relatively coarsely classified into the following subgroups:
- Fluxing agents: These are chemicals that, when added, primarily serve to lower the melting temperature of glazes/glass.
- Glass-forming agents: These are substances that, when involved in the composition of glazes, primarily serve to create glass.
- Coloring agents: These are chemicals that, when added, primarily serve to produce certain colors or shades for glazes/glass.
- Opacifying agents: These are chemicals that, when added to the mixture, primarily serve to create certain opacities for the colors of glazes/glass.
- Burnout materials: These are substances that, when heated at high temperatures, will decompose and escape in gaseous form. However, they may participate in some complex chemical reactions whose mechanisms have not yet been thoroughly studied.
- Other substances: This subgroup contains substances present in glazes at very small percentages (trace amounts).
However, this classification is not entirely accurate, as the role of a specific chemical also depends on the firing environment (oxidizing, reducing, or neutral), the presence of other chemicals, as well as the firing temperature, etc.
Fluxing agent
BeO
Molecular weight: 25.011 g/mol
Melting point: 2,650°C
Name: beryllium oxide
Source: beryl
Beryllium oxide is a special oxide, as it exists in a nearly pure form in nature. It is used to create ceramic materials with high thermal conductivity, especially in low-temperature environments.
Bi2O3
Molecular weight: 466 g/mol
Melting point: 820°C
Name: Bismuth oxide
Source: Bismuth nitrate
Bismuth oxide is released from the heating of bismuth nitrate. Bismuth can effectively replace lead, and it also provides gloss, fluidity, refractive index, surface tension, and viscosity similar to glazes. Bismuth melts at a lower temperature than lead, thus glazes can be more fluid. However, bismuth is more expensive than lead, and in some cases, the glaze may not have the same gloss as when using lead oxide, for example, in the case of cobalt blue or iron red printed on the glaze. Bismuth is also used in low-fire frit glazes and colors.
CdO
Molecular weight: 128.41 g/mol
Melting point: 1,426°C
Name: Cadmium oxide
Source: Cadmium sulfide, cadmium silicate
Cadmium oxide is insoluble in water and alkaline solutions but soluble in acidic environments and ammonium salt solutions. It does not impart color to glazes by itself; however, when used with selenium oxide, it produces a red color; with sulfur, it produces a yellow color.
K2O
Molecular weight: 94.2 g/mol
Expansion coefficient: 0.331
Melting point: 750°C
Name: Potassium oxide
Source: Potassium feldspar, Cornwall stone, nepheline syenite, frit
K2O, along with Na2O and Li2O, forms the group of alkali oxides. K2O is often used together with Na2O in the raw material preparation stage, and they have almost identical properties. When used together, they are referred to as KNaO. As a very stable oxide, potassium oxide is an important fluxing agent in high-fire glazes. Its high thermal expansion contributes to glaze crazing, but not as severely as sodium oxide. Alkali glazes are almost always crazed. If the desired color of the glaze depends on the alkali content, the only way to avoid crazing is to adjust the body of the clay.
Na2O
Molecular weight: 62 g/mol
Expansion coefficient: 0.387
Melting point: 800 °C
Name: Sodium oxide
Source: Feldspar, nepheline syenite, sodium frit, soda
Sodium oxide is a slightly stronger flux than potassium. Sodium oxide is usually added through soda. High thermal expansion can easily cause glaze cracking. Sodium can begin to vaporize at high temperatures. It creates strong colors with copper, cobalt, iron, however, the high tendency to crack the glaze and the glaze being too thin due to the high soda content. High alkali and low alumina help achieve the best colors. Alkali increases the solubility of lead in the glaze.
KNaO
Molecular weight: 78.1
Expansion coefficient: 0.359
Name: Potassium/sodium oxide
Source: K2O and
Molecular weight and expansion coefficient are the average values of the two component oxides.
Li2O
Molecular weight: 29.8
Expansion coefficient: 0.068
Melting point: 1,000 °C
Name: Lithium oxide, lithia
Source: Lithium carbonate, lithium feldspar or spodumene
Li2O is the strongest flux oxide. Along with boron oxide and sodium oxide, it acts as a fluxing agent. Just using 1% will significantly improve the gloss of the glaze, 3% greatly reduces the melting points of the glaze and decreases the surface tension of the molten glaze. Its thermal expansion is much lower than that of sodium and potassium, thus it is used for glazes that require very low expansion. It affects the textural effects of the glaze surface. Li2O increases the opacity of the glaze. Li2O with copper oxide can produce blue color. Li2O with cobalt oxide can produce pink color.
MgO
Molecular weight: 40.3
Expansion coefficient: 0.026
Melting point: 2,800°C
Name: Magnesium oxide, Magnesia
Source: dolomite, magnesium carbonate
Along with SrO, BaO, and CaO, they form the group of alkaline earth oxides. Zirconium oxide and magnesium oxide are the two oxides with the highest melting points. However, MgO easily forms eutectic phases with other oxides and melts at very low temperatures. Low thermal expansion and resistance to glaze cracking are two important characteristics of magnesium oxide. In high-temperature glazes, it is a fluxing oxide (starting to act from 1,170°C) that produces a liquid glaze with high viscosity, high surface tension, opaque, and dull. Like CaO, its effect on melting glaze increases very rapidly as the temperature rises. MgO should not be used for bright-colored glazes. It can also adversely affect some colors of the base glaze. MgO is used as a surface additive to create a matte glaze.
MoO3
Molecular weight: 143.94
Expansion coefficient: 0.094
Melting point: 795°C
Name: Molybdenum oxide
PO4
Molecular weight: 94.969
Name: Phosphorus oxide
Source: bone ash
PbO
Molecular weight: 223.2
Expansion coefficient: 0.083
Melting point: 888°C
Name: Lead (II) oxide
Source: lead frit, lead oxide
Easily reacts with silica to form lead silicate that melts at low temperatures, with high gloss. Lead (II) oxide can provide unusual surface characteristics and colors. Lead glaze also has a high resistance to edge chipping. Lead carbonate, the best source of lead oxide, exists almost in pure form and has a very fine particle size. It helps to form and maintain a good suspension in unburned glaze as well as helps the glaze melt at low temperatures. Low thermal expansion, used in combination with boron oxide to improve crazing and chemical corrosion resistance. Lead (II) oxide also thins the melted glaze. The problem with lead is its toxicity, loss of gloss when fired at high temperatures, cloudiness after prolonged use, and poor abrasion resistance. If too much lead is added, long-term users will be affected in their mental capacity...
ZnO
Molecular weight: 81.4
Expansion coefficient: 0.094
Melting point: 1,800°C
Name: Zinc oxide
Source: Zinc oxide
ZnO begins its fluxing function at around 1,000°C. However, ZnO is easily reduced to metallic zinc by CO and H2 gases in the reducing atmosphere of a gas kiln (or electric kiln with poor ventilation). Pure metallic zinc melts at 419°C, boils and vaporizes at 907°C. ZnO has low thermal expansion and can be used instead of high thermal expansion fluxes to prevent crazing. At average and high usage levels, ZnO gives a dull and crystalline glaze. The reaction of zinc oxide on colors is quite complex. It can have beneficial or harmful effects on blue, brown, green, pink colors and is advised not to be used with copper, iron, or chromium. At high levels, ZnO can be a opacifier (milky white).
FeO
Molecular weight: 71.85
Melting point: 1,370°C
Name: Iron (II) oxide, black iron oxide
Source: Black iron oxide
In a reducing environment, Fe2O3 is easily reduced to FeO according to the following reaction at 900°C:
Fe2O3 + CO = 2FeO + CO2
The above reaction occurs easily if the clay contains many organic impurities. Once trivalent iron has been reduced to divalent iron in the glaze, it is very difficult to oxidize back.
FeO is a strong flux oxide that can replace lead oxide or calcium oxide. Most types of glazes will have a higher solubility of divalent iron when melted than when in a solid state, thus there will be crystallized iron oxide in the glaze when cooled, in an oxidizing or reducing environment.
Glass former
Free SiO2
Molecular weight: 60.1
Coefficient of expansion: 0.035
Melting point: 1,710°C
P2O5
Molecular weight: 141.9
Melting point: 580 °C
Name: Phosphorus pentoxide
Source: Bone ash, wood ash, charcoal ash
P2O5 is a glass-forming substance like boron oxide and silica. Phosphor glass tends to create grayish-green streaks in glazes; it does not participate in the silica chain but exists as a separate colloidal entity within the silicate network. P2O5 can be used as a surface modifier, and it can create various effects and speckles in glazes (especially with low-fired glazes) when used in low amounts (up to 2%). Bone ash is a source.
Colorant
CeO2
Molecular weight: 172
Melting point 2,400°C
Name: Cerium oxide, Cerium (IV) oxide
Used for optical glass because it has protective properties against ultraviolet rays. Combined with titanium for a yellow color. Used as a opacifier in cases where some special effects are needed in the ceramics industry.
Cu2O
Molecular weight: 143
Melting point: 1,235°C
Name: Copper (I) oxide
Source: Red copper oxide. See also: Copper (II) oxide
The reducing firing environment will convert CuO (black) to bright red Cu2O:
2CuO + CO = Cu2O + CO2
To achieve a bright red color, only a very small amount of copper (I) oxide (0.5%) is needed. If the copper content is higher, it may lead to the appearance of tiny metallic copper particles in the molten glaze, resulting in a red color known as de-boeuf. If boron is present in the red copper glaze, a purple color will be obtained. In red copper glazes, many feldspar materials are used, and adding barium oxide produces colors ranging from earthy green to deep blue, depending on the copper oxide content. Fluorine, when used with copper oxide, gives a bluish-green color.
CuO
Molecular weight: 79.54
Melting point: 1,148°C
Name: Copper (II) oxide
Source: Black copper oxide
In a normal oxidizing environment, CuO is not reduced to Cu2O and it gives a translucent green color to the glaze. A purple color can be created for the glaze if there is a little green copper oxide (CuO) and a little red copper oxide (Cu2O) in the glaze. This effect is usually achieved if the glaze has a high CaO (quicklime) content or if the initial firing process is in an oxidizing environment and the subsequent stages are in a neutral environment. The green color can vary depending on the firing rate. The most beautiful color is achieved with fast firing. The shade of green also depends on the presence of other oxides (for example: high lead content will give a darker green color, high alkaline earth or boron oxides will lean towards a bluish hue). Copper oxide is a fairly strong flux. It increases the fluidity of the molten glaze and enhances the ability to create crazing due to its high thermal expansion coefficient. Combined with titanium oxide, it can create very beautiful "stain" and "spot" effects. CuO combined with tin or zircon gives a Thoreau blue or green-blue color in alkaline earth glazes (high KNaO content) and low alumina. It is advisable to use pre-mixed frit if you want this color, however, this type of glaze often tends to craze. CuO in (barium/zinc/sodium) glazes gives a blue color. K2O can make glazes with CuO take on a yellowish hue.
Fe2O3
Molecular weight: 159.69
Expansion coefficient: 0.125
Melting point: 1,565°C
Name: Iron (III) oxide, red iron oxide, rust
Source: Iron oxide, clay with reddish-brown stains...
Iron compounds are the most common colorants in the ceramics industry. Iron can exhibit different characteristics depending on the kiln environment, firing temperature, firing time, and the chemical composition of the glaze. Therefore, it can be said that it is one of the most interesting raw materials. Chemically, iron (III) oxide is also amphoteric like alumina. Fe2O3 is not a fluxing oxide; it is a non-fluxing agent. In a reducing environment, Fe2O3 can easily be reduced (by carbon or sulfur compounds in the raw materials and kiln environment) to FeO and become a fluxing agent. If one wants to retain iron (III) oxide, the firing environment must be oxidizing at temperatures between 700 °C and 900 °C. Iron (III) oxide is the most common form of natural iron oxide. In an oxidizing firing environment, it remains Fe2O3 and gives glazes a color ranging from amber to yellow if the maximum content in the glaze is 4% (more pronounced if the glaze contains lead (II) oxide and lime), gives a tan (brown-yellow) glaze if the content is around 6%, and produces a brown color if the iron (III) oxide content is higher. The red color of iron (III) oxide can vary over a wide range in low firing temperatures. If fired at low temperatures, it appears bright orange. As the temperature increases, the color shifts to bright red, then dark red, and finally brown. The transition from red to brown occurs abruptly over a narrow temperature range, which should be noted.
Most types of glazes will have a higher solubility of ferric iron when melted than in a solid state, thus there will be crystallized iron oxide in the glaze when cooling, in oxidizing or reducing environments. Glazes with high flux content and low melting points will dissolve more iron.
Zinc negatively affects the color of iron.
Titanium and rutile (titanium dioxide) with iron can create very beautiful speckled or streaked effects.
In reduction glazes with ferric oxide, the glaze will have colors ranging from earthy green to light green (when the glaze has a high soda content, with boron oxide).
In glazes containing calcium, ferric oxide tends to give a yellow color. In alkaline glazes, it gives colors ranging from straw yellow to brownish yellow.
Low-fired lead glazes, potassium and sodium glazes are red when ferric oxide is added (in the absence of barium).
Fe3O4
Magnetite: it can be a mixture of Fe2O3 and FeO. The result of the incomplete conversion reaction or it can be a form of naturally occurring crystalline mineral, giving a brown color. The latter is used to create tiny brown specks in the glaze. Adding Fe2O3 to the glaze helps reduce glaze crazing (if the amount used is below 2%).
InO3
Molecular weight: 277.64
MnO
Molecular weight: 70.9
Expansion coefficient: 0.05
Melting point: 1,650°C
Name: Manganese (II) oxide
Source: Manganese dioxide
At temperatures above 1,080°C, MnO2 converts to MnO (MnO only exists at temperatures above 1,080°C) – MnO is a fluxing oxide that easily combines with silica to produce a purple color if there is no alumina in the glaze and a brown color if alumina is present. Manganese brown is different and more beautiful than iron brown.
Small amounts of MnO easily dissolve in most types of glazes; however, above 5%, MnO begins to precipitate (the cooling rate and the fluidity of the glaze will affect the precipitation). If the content is very high (20%), a metallic surface will occur.
MnO does not change in a reducing environment; however, it is still best to use it in an oxidizing environment and during firing at temperatures above 1,200°C.
In firing below 1,080 °C, manganese oxide gives a coffee brown color in the presence of tin, and a dull brown color in the presence of lead and low alkali content.
MnO2
Molecular weight: 86.9
Expansion coefficient: 0.05
Melting point: 1,080°C
Name: Manganese dioxide, Manganese (IV) oxide
Source: Manganese dioxide
MnO2 can produce a purple color in high alkaline glaze (KNaO) and low alumina, with the presence of cobalt oxide being even better (it is recommended to use frit with this composition).
Color spots with a composition of 8 iron, 4 manganese, and 0.5 cobalt give a deep black color.
NiO
Molecular weight: 74.7
Melting point: 1,453°C
Name: Nickel (II) oxide
Source: Nickel oxide
Usually not used with low-fired glazes due to the high melting point of nickel (II) oxide powder. Dull glazes will dry out if nickel (II) oxide is added.
Nickel (II) oxide is often used to enhance and "soften" the color of other metal oxides, thus it is only used in small amounts.
Nickel (II) oxide with tin oxide gives a steel blue color. If the tin content is high, it may have a lavender color. Nickel (II) oxide and calcium oxide give a brownish-yellow color. Nickel (II) oxide with barium oxide gives a brown color. Nickel (II) oxide in lead glaze gives a gray color. Nickel (II) oxide can give a pink color in high potassium glaze. Nickel (II) oxide gives a yellow color in lithium glaze. Nickel (II) oxide with high MgO content gives a green color, better if zinc is present.
PrO2
Molecular weight: 172.9
Name: Praseodymium (IV) oxide
Source: Colorant
Used together with zircon in various types of lemon yellow stains. The yellow color can vary depending on the chemical composition of the glaze. PrO2 glaze can easily be discolored when contaminated with other colored oxides.
PrO2 can be used in reducing environments at high temperatures. It is also toxic but less dangerous than vanadium or antimony.
Se
Molecular weight: 111.2
Melting point: 217 °C
Name: Selenium
Source: Sodium selenide, barium selenide
A metalloid element in the sulfur group. Used with cobalt, it will be a good color reducer for glass, as it creates a pink color that neutralizes the green color of iron, and the glass will be colorless and transparent. Used with cadmium for red glaze (low firing). The presence of lead enhances the color. Gives glass a rose or ruby color. Used in some special types of colorants.
U3O8
Molecular weight: 842
Melting point: 2,176 °C
Name: Uranium oxide
Source: Uranium oxide
Can be considered a mixture of UO2x2UO3. Used as a colorant, the usage content can be up to 15%, and can give yellow, red, and orange colors. For example, uranium oxide gives a red color in lead silicate glaze with low alumina and no boron oxide, the presence of zinc is even better. Although the oxide form is considered not dangerous in terms of radioactivity, the use of uranium in general should be limited.
V2O5
Molecular weight: 181.9
Melting point: 690 °C
Name: Vanadium pentoxide
Source: Vanadium oxide
Vanadium is a metallic oxide with acidic properties, giving a yellow color when used at a concentration of about 10%. Its color is weak; however, it can also be used in combination with tin and zirconium oxide. The yellow color of vanadium is more stable than that of antimony yellow at high temperatures. The vanadium color is most brilliant and impressive in lead glaze. Vanadium pentoxide is also a strong fluxing agent. In addition to V2O5, we can also have V2O3.
Opacity agent
Sb2O3
Molecular weight: 291.6
Melting point: 630 °C
Name: Antimony oxide (III)
Source: Antimony oxide, antimony sulfide
Antimony oxide (III) is used as an opacifying agent in low-fire glazes; however, it can easily lose its opacifying properties because it is a reducible substance. Therefore, an oxidizing agent such as KNO3 must be included in the glaze to ensure this phenomenon does not occur. It cannot be used for glazes fired above cone 1 due to volatilization. It can give the glaze a Naples yellow color if lead is present (forming yellow lead antimonate precipitate).
SnO2
Molecular weight: 150.7
Expansion coefficient: 0.02
Melting point: 1,127 °C
Name: Tin oxide (IV), Stannic oxide
Source: Tin oxide powder
The highest oxide form of metallic tin. Tin(IV) oxide is very white, with a low density. Metallic tin melts at a very low temperature, but tin(IV) oxide only melts at 1,127 °C.
SnO2 is primarily used as an opacifier (with a usage amount of 5-15%) for all types of glazes. Tin oxide is an effective opacifier for converting glazes into a white opaque (soft white with a bluish tint compared to the coarse pure white of zircon). The amount used depends on the glaze composition and firing temperature. The opacifying feature of tin oxide is due to the small tin oxide particles being dispersed and suspended in the fired glaze. At higher temperatures, the tin oxide particles begin to melt, dissolve, and will lose their opacifying ability.
Like zircon oxide, a high amount of tin oxide in low-fired glazes will make the glaze difficult to flow, thicken the flowing glaze, and increase the likelihood of pinholes and spikes. Using tin oxide will yield a softer white color compared to using zircon-based opacifiers (which are very common and much cheaper than tin oxide). One must be very careful as tin oxide easily reacts with chromium (even a very small amount) producing a pink color. If there is only a little chromium vapor from other types of glazes in the kiln, the white color of tin oxide will be lost. Other opacifiers include zircon oxide (which gives a coarser glassy white), calcium phosphate (which has issues turning gray), cerium oxide (only used at low temperatures), antimony oxide (problematic if the glaze contains lead – the glaze turns yellow), and titanium dioxide (loses color if iron oxide is present).
TiO2
Molecular weight: 79.9
Expansion coefficient: 0.144
Melting point: 1,830 °C
Name: Titanium dioxide, Titania
Source: Titanium dioxide, rutile
Titanium dioxide is a versatile oxide as it can act as an opacifier, create spots, and crystallize. A content of less than 0.1% is used to alter the color of glazes derived from other metal oxides such as Cr, Mn, Fe, Co, Ni, and Cu. Titanium dioxide can self-generate glass, but it does not have high solubility in molten silica. At a content of less than 1%, titanium dioxide is completely soluble in molten glaze (it cannot yet act as an opacifier). At slightly higher levels, it will produce a bluish-white streak in transparent glaze (depending on the alumina content). Above 2%, it begins to significantly alter the surface and opacity of the glaze due to the formation of suspended crystalline particles in the glaze. In the range of 2-6%, it will create spots on the glaze surface. From 10-15%, it gives the glaze surface a cloudy and dull edge if the glaze is not over-fired. Titanium dioxide is an "oxygen-hungry" oxide and is easily oxidized from its reduced form when given the opportunity.
Titanium dioxide is used in some types of lead frit to reduce permeability. Glazes containing titanium dioxide can change color slightly under the influence of light and can also change color due to the effects of heat. TiO2 is considered an inert oxide in glazes. However, on the Al2O3 - TiO2 phase diagram, titanium dioxide and aluminum oxide form the same eutectic phase at 80% Al2O3 and 1705 °C, indicating that TiO2 reacts with aluminum oxide, the second most important oxide in the ceramics industry.
ZrO
Molecular weight: 107.2
Expansion coefficient: 0.02
Name: Zirconium oxide (II), Zirconia
Source: Zircon opacifiers, zirconium silicate
ZrO can create patterns consisting of alternating light and dark areas on the glaze surface (surface modifier). A high content (about 15%) must be used. Zircon is used in spots to stabilize color.
ZrO2
Molecular weight: 123.2
Expansion coefficient: 0.02
Melting point: 2,700 °C
Name: Zirconium dioxide, Zirconium oxide (IV)
Source: Zircon opacifiers, zirconium silicate
It is used as a opacifier in glazes, similar to tin oxide. However, tin oxide can be said to be twice as effective in terms of opacity. High boron or alkaline glazes, low alumina and silica glazes may not be very well opacified.
LOI (Loss on Ignition)
Acronym for the English term Loss on Ignition
C
Name: Carbon
Source: ball clay
CO2
Name: Carbon dioxide
CO2 is produced when carbon in the raw material burns during the firing process. CO2 is typically generated when CO gas in the combustion chamber (produced in a reducing or incomplete oxidation environment) encounters compounds from which it can easily take an oxygen atom to form CO2.
H2O
Source: clay, hydrated minerals (hydration)
F
Molecular weight: 19
Name: Fluorine
Fluorine is released when firing certain materials such as Cornwall stone or fluorspar, its fumes are highly toxic, therefore it must be noted separately and should not be grouped into LOI.
Other substances
Trace elements (or microelements)
Use the group of trace elements in the analysis table but consider their weight as 0 in the calculation of glaze formulas.
Y2O3
Molecular weight: 225.8
Melting point: 2,585 °C
Name: Yttrium oxide
Used in the manufacture of conductive ceramics, refractory materials, the glass industry, and in color stains. Can give a yellow glaze.
Color developing glaze
Color-developing glaze (Archived 2008-10-09 at Wayback Machine(colored glaze)) is a type of glaze that contains colored metal oxides or salts in its composition, which when heated, create a rich variety of color effects. Thus, the colored metal oxides and salts are the main factors that create the glaze color. The firing process is also a very important factor that determines the color and effects of the glaze. For precious glazes, even a small change in the firing process can completely alter the glaze color. Each ceramic artisan often seeks out their own formulation and firing method, considered a trade secret, to achieve the desired colors. The more unique the colors combined with interesting effects, the more valuable the glaze, the more valuable the product, and the higher the recognition of the ceramic artisan's status. Celadon glaze, blood-red glaze, crystalline glaze... are typical examples of valuable color-developing glazes.
Polymer materials
Polymer is a term used for high molecular weight compounds (compounds with large molecular weights and in their structure, there are repeated basic links many times). Similar molecules with lower molecular weights are called oligomers.
The term polymer comes from the Greek, πoλvς, polus, 'many' and μερος, meros, 'part', meaning large molecules formed from the repetition of many smaller molecules. The units that create polymers originate from molecules (real or imaginary) with relatively low molecular weights. This term was coined by Jöns Jacob Berzelius in 1833, although he had a definition that differed from modern IUPAC definitions. The modern concepts of polymers as covalent macromolecular structures were proposed by Hermann Staudinger in 1920. He spent the following decade seeking experimental evidence for this hypothesis.
Polymers are commonly used in practice under the name plastic, but polymers consist of 2 main types: natural polymers and synthetic polymers. Organic polymers such as proteins (for example, hair, skin, and part of bones) and nucleic acids play a major role in the synthesis of organic polymers. There are many forms of natural polymers that exist, such as cellulose (the main component of wood and paper).
Composite materials
Composite materials, also known as composite materials, composite materials, or composites, are materials synthesized from two or more different materials to create a new material with properties that are significantly superior to the original materials when these materials work separately.
Simple composites have existed since ancient times. About 5000 years ago, humans knew to mix small stones into the soil before making bricks to prevent warping when exposed to sunlight; a typical example of composites is the compound used to embalm the bodies of Egyptians.
Nature itself first created the composite structure, which is the trunk of a tree, having a composite structure, consisting of many long cellulose fibers connected by lignin. The result of this harmonious bonding is that the trunk is both strong and flexible - an ideal composite structure.
Ancient Greeks also knew to mix honey with soil, stones, and gravel to make building materials; and in Vietnam, there was an ancient method of making houses with mud mixed with finely chopped straw to plaster the walls, which, when dry, creates a hard material that is cool in summer and warm in winter...
Although composites are materials that have existed for a long time, the science of composite materials has only recently formed in connection with the emergence of rocket manufacturing technology in the U.S. since the 1950s. Since then, the science and technology of composite materials have developed worldwide, and sometimes the term "new materials" is synonymous with "composite materials."
1.1. Composite Materials
Composite materials are a type of material made from two or more different phases. One of the phases, called the matrix, is usually a type of polymer, such as plastic, that surrounds and protects the reinforcing layer. The reinforcing layer, which can be made from fibers or particles, provides the strength and stiffness of the composite material.
1.2 The Development of Composite Materials
The concept of composite materials has existed since ancient civilizations, where natural materials like mud bricks and wood were used in construction. The modern era of this type of material began in the early 20th century with the development of synthetic plastics and fibers. The use of composite materials became widespread during World War II. They were used to replace traditional materials in aircraft manufacturing.
1.3. Main characteristics and advantages
Composite materials offer several important advantages over traditional materials, including:
Improved strength and stiffness: Biocomposite compounds are often reinforced with strong fibers, such as fiberglass or carbon fiber, to enhance their strength and stiffness. This is because the reinforcing phase, such as fibers or particles, can be oriented in a specific direction to provide maximum strength and stiffness in that direction.
Lightweight: Biodegradable fillers can help make the material lighter, as they are lighter than traditional materials like wood flour or cellulose. This is due to the matrix phase, which is usually a type of plastic, being lighter than the reinforcing phase.
Ductility and toughness: With ductile properties, they can deform without breaking and can absorb energy before fracturing. This is crucial for applications that require materials to withstand impact or fatigue.
Heat and corrosion resistance: Engineering plastic compounds are often made from heat and corrosion-resistant polymers, such as nylon or polypropylene.
Flexibility in design: Composite materials can be designed to have many different properties, making them versatile for various applications.
Fiberglass composite materials are the backbone of marine applications.
If materials are categorized by application sectors, there are:
- Electrical materials
- Electronic materials
- Construction materials
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