Ocsaíd siorcóiniam agus ocsaíd alúmanaim a chur le chéile Zirconia Toughened Alúmana (ZTA), ábhar eisceachtúil i go leor iarratas. Airíonna meicniúla, neart, toughness briste, leaisteachas, tá ard-mheas ar chruas agus ar fhriotaíocht chaitheamh san ábhar ceirmeach ilchodach seo a bhaineann leis an rang de chomhchodanna AZ. ZTA anois an rogha is fearr le haghaidh neart meicniúil ard, friotaíocht teirmeach agus friotaíocht creimeadh.
An Comhdhéanamh agus an Struchtúr a Dhíchódú
I measc rudaí eile, Is éard atá i Zirconia Toughened Alumina ná gráin zirconia scaipthe go haonfhoirmeach laistigh de mhaitrís alúmana. Go hiondúil, áirítear leis seo 10-20% toirt ZrO2 in alúmana. Ag brath ar a gcuid comhréireanna, cuireann meascáin comhábhair le criadóireacht le gnéithe sonracha ag brath ar iarratas ar leith.
Bloic Tógála: Alúmana agus Zirconia
Is iad na príomhchodanna a mheasctar chun ZTA a fhoirmiú ná alúmana agus zirconia. Thairis sin, tá ionchlannáin ortaipéideacha ag baint úsáide as an ábhar ceirmeach seo ar a dtugtar Ocsaíd Alúmanam (Al2O3) sa stair mar gheall ar a biocompatibility maith chomh maith lena neart meicniúil iontach agus friotaíocht briste.
Maoin eile den scoth de zirconia ná a rátaí íseal creimthe chomh maith le cobhsaíocht mhaith ceimiceach agus neart meicniúil ard. Tá modulus a Young san ord céanna méide le cóimhiotail cruach dhosmálta.
Conas a Dhéantar é
Chun ZTA a tháirgeadh ciallaíonn sé go gcruthófar grán zirconia de chéim tetragonal a dháileadh go haonfhoirmeach ar fud maitrís alúmana. A crack tip stress concentration can alter a tetragonal crystal structure into a monoclinic one thereby leading to an associated increase in volume of zirconia. Such volume expansion effectively reverses or stops the growth of crack leading to greater toughness and strength.
Mechanical Properties of ZrO2-Al2O3 Ceramics
There is a wide range of mechanical properties exhibited by ZTA including superior hardness than conventional aluminas with similar density values, higher flexural strength than conventional aluminas and lower than conventional zirconias coefficient of linear thermal expansions (CLTE).
Zirconia Toughened Alumina has high mechanical strength and is thermally resistant hence it does not corrode. Below are some of ZTA’s properties:
Luach Maoine
Foirmle Cheimiceach Zr-Al2O3
Dlús 4.1-4.38 g/cm^3
Cruas 1750-2100 Cnaipe
Leaisteachas 45-49 x 10^6 psi
Neart Solúbtha 100-145 ksi
Poisson’s Ratio 0.26
Toughness Briseadh 5-7 MPa m^ 1/2
Comhéifeacht Leathnú Teirmeach 8.0-8.1 x 10^-6 1/C
Seoltacht Theirmeach 20.0-21.0 W/mK
Friotaíocht turrainge 325 °C
Teocht Oibre Uasta 1650 °C
Applications of ZrO2-Al2O3 Ceramics
Zirconia Toughened Alumina is used in various applications such as those which require high strength and wear resistance. These include valve seals, sleeves, pump pistons, spraying nozzles and other industrial parts.
Biocompatibility of ZTA
In various studies, ZTA has been reported to produce no adverse tissue reaction upon implantation thus making it a good candidate for orthopedic load-bearing components. In addition, the hardness, toughness and strength exhibited by zirconia-alumina ceramics make them fit for orthopedic load-bearing components.
ZTA in Hip Arthroplasty
There have been considerable deliberations on ceramics like alumina, zirconia and zirconia toughened alumina (ZTA) as suitable materials in hip arthroplasty . These advantages of ZTA were achieved without having to incorporate the disadvantages associated with yttria-stabilized zirconia that exhibits high mechanical properties or alumina with its high inertness.
ZTA in Knee Arthroplasty
Mostly, ceramic implant designs for total knee arthroplasty (TKA) have been developed in order to handle the issue of allergic reactions that may occur in patients when modern titanium or cobalt-chromium alloy components release wear particles. The Zirconia Toughened Alumina (ZTA) Matrix Composite is a cutting edge biomaterial for such applications.
ZTA: The Promising Future
This involves continuous research as well as development on ways improving ZTA’s attributes and its potential uses. Another batch-processed Zirconia Toughened Alumina has been designed with mechanical properties in terms of flexural strength substantially lesser than those from commercially available Biolox® Delta. Another, such as silicon nitride ceramics composites introduced recently into hip arthroplasty also exhibits higher strength than alumina.The future is bright for ZTA with many applications and superior properties. Therefore, with evolving technology, it is expected that ZTA will be the basis for new concepts on various fronts especially on biomedicine.