Neprilygstamas tvirtumas su cirkoniu grūdintu aliuminio oksidu (ZTA) Keramika

Cirkonio grūdintas aliuminio oksidas (ZTA) keramika pasižymi neprilygstamu tvirtumu. Jie pasižymi puikiu atsparumu dilimui, Cheminis inertiškumas ir maža trintis leidžia lengvai atlikti kasdienes užduotis – jau nekalbant apie didesnį kietumą ir standumą nei metalai.

ZTA apima metastabilius tetragoninius cirkonio oksido polikristalinius aglomeratus aliuminio oksido matricoje, kurie patiria streso sukeltą fazės transformaciją į monoklininę formą., taip išsklaido šlyties įtampą ir sustabdo plyšių plitimą, paprastai žinomas kaip transformacijos grūdinimas.

Atsparus korozijai

ZTA pasižymi puikiu cheminiu atsparumu, lyginant su grynu aliuminio oksidu, ir gali atlaikyti ekstremalias temperatūras be degradacijos, todėl tai idealus medžiagų pasirinkimas pramoniniam naudojimui atšiaurioje aplinkoje ir sąlygomis.

ZTA tvirtumą padidina cirkonio dalelės, kurios išsklaido ir sugeria energiją, padedantis išvengti įtrūkimų. Kai legiruotas itrio oksidu, cirkonis keičiasi iš metastabilios tetragoninės fazės į monokliniką streso metu, kad susidarytų gniuždymo įtempiai, kurie padidina atsparumą lūžiams.

Cirkonio dioksido pagrindu pagamintoje keramikoje, pvz., ZTA, yra aliuminio oksido dalelių, kurios atsparios šiluminiam smūgiui. Tai leidžia atlaikyti greitus temperatūros pokyčius be įtrūkimų ar gedimų atliekant didelio našumo programas, tokias kaip šlifavimas ir pjovimas; mažas tiesinis ir sukimosi plėtimasis užtikrina išskirtines apkrovas ir našumą. ZTA giriasi 2-3 kartų stipresnis tempiamasis stipris, palyginti su grynu aliuminio oksidu, tuo pat metu turintis mažus linijinio / sukimo plėtimosi koeficientus, užtikrinančius išskirtinę apkrovą ir našumą.

High Stiffness

ZTA combines the strength and durability of alumina with zirconia toughening for an exceptional material for demanding applications. This combination offers unparalleled strength, lūžimo atsparumas, elasticity and hardness properties in one package.

Claussen discovered in 1976 that adding unstabilized zirconia to alumina significantly increases its fracture toughness, due to the tetragonal-monoclinic transformation of dispersed fine tetragonal precipitates dispersed within its matrix. Such metastable precipitates are restrained from changing until released by an approaching crack front or other source of relief from their constraint, such as by melting away.

Hot-pressed 10mol% yttria-stabilized zirconia (10YSZ), reinforced with either particulates or platelets containing from 0 to 30wt% alumina content were subjected to rigorous strength, fracture toughness and slow crack growth tests at 1000C in air. Results demonstrated that maximum flexural strength and fracture toughness for platelet composites was attained with this composition content.

High Tensile Strength

Zirconia ceramics offer an extraordinary combination of strength, resilience, and versatility that far outshines traditional technical ceramics. Zirconia formulations like ZTA provide solutions for today’s most difficult applications ranging from aerospace components enduring harsh environments to next-generation biomedical implants designed for longevity – providing reliable solutions for today’s most pressing needs.

ZTA stands out amongst other materials due to its superior flexural strength, fracture toughness and resistance to crack propagation due to its metastable tetragonal phase. This transformation into monoclinic zirconia at low temperature compresses the zone ahead of a crack front to stop further growth.

Yttria Partially Stabilized Zirconia (Y-TZP) and Cerium Partially Stabilized Zirconia (Ce-TZP) exhibit exceptional toughness characteristics similar to ZTA due to the retention of tetragonal phase by maintaining yttria or cerium at lower temperatures, permitting transformation at a more manageable temperature range and showing less surface damage during cyclic loading tests than Alumina counterparts.

Low Friction

Zirconia is one of the hardest engineering ceramics available and its low friction properties help increase wear resistance while decreasing lubrication requirements.

ZTA ceramics contain alumina for maximum toughness. This allows metastable yttria-stabilised tetragonal zirconia particles in an alumina matrix to remain unaltered, remaining crystalized by virtue of an interwoven network of grains.

Controlled composition and processing conditions ensure that spontaneous tetragonal-to-monoclinic transformation does not occur upon cooling from the sintering temperature, contributing to multi-hit capability in fracture toughness testing. Be to, high homogeneity in alumina-zirconia composites with small grain sizes results in lower crack energy which in turn translates to shorter crack lengths during diamond indentation tests.

High Thermal Expansion

Alumina matrix’s binding force enables it to prevent the tetragonal zirconia particles from transitioning into monoclinic zirconia upon cooling, thus making 10 mole % yttria-stabilized zirconia-alumina composites stable and crack free.

Addition of cerium to zirconia allows it to be partially stabilized (Ce-TZP). Ce-TZP keeps its tetragonal phase at room temperature and significantly increases toughness, fracture toughness and flexural strength compared to traditional dental ceramic materials.

Zirconia Toughened Alumina composites incorporating Ce-TZP, yttria-stabilized zirconia (Y-TZP), or magnesia-stabilized zirconia (Mg-PSZ) exhibit exceptional toughness that surpasses that of both alumina and monolithic zirconia, making ZTA the perfect candidate for demanding applications like medical implants, aerospace components and industrial machinery. ZTA also boasts many chemical resistance properties that protect it against acids, salt solutions, molten salts alkalis as well as high temperatures.