Calcium silicon alloy (CaSi)yog ib tug tseem ceeb multifunctional additive nyob rau hauv cam khwb cia hlau ntau lawm. Los ntawm plaub lub luag haujlwm tseem ceeb - graphite hloov kho, deoxidation thiab purification, grain refinement, thiab sulfur tswj- nws comprehensively txhim khu lub zog, toughness, machinability, thiab kev cia siab ntawm cam khwb cia hlau, ua rau nws haum rau siab - kawg daim ntaub ntawv xws li automotive qhov chaw thiab muaj machinery.
Lub cev muaj zog:Melting point 1250-1350 degree, ceev 2.5-2.8g/cm³, silver-grey block (5-30mm) los yog hmoov, calcium nkag volatilizes ntawm qhov kub thiab txias, muaj zog reactivity, thiab muaj zoo compatibility nrog molten hlau;
Core zoo:Multifunctional kev koom ua ke (spheroidization + deoxidation + refining), ntxiv 0.2%-0.5% ib tuj ntawm cam khwb cia hlau tuaj yeem ua tiav ntau- qhov kev ua tau zoo, nrog rau kev ua haujlwm zoo;
Core mechanism ntawm silicon calcium alloy txhim kho cam khwb cia hlau kev ua tau zoo
(1) Graphite hloov kho: los ntawm "flake" mus rau "spheroid", toughness doubles
Mechanism ntawm kev ua:
Silicon txhim kho cov pa roj carbon monoxide hauv molten hlau, txhawb graphite nucleation; Calcium, raws li tus neeg sawv cev spheroidizing, adsorbs ntawm qhov chaw ntawm graphite nuclei, inhibiting flake kev loj hlob thiab coj kev tsim ntawm spheroid/worm-zoo li graphite;
Cov tshuaj tiv thaiv tseem ceeb:
Calcium ua ke nrog sulfur thiab oxygen, tshem tawm lawv cuam tshuam nrog graphite spheroidization, thaum lub generated CaC₂ tuaj yeem ua lub graphite nucleation core.
(2) Deoxidation thiab Purification: Txo kev suav nrog thiab txhim kho purity.
Mechanism ntawm kev ua:
Silicon reacts nrog oxygen: Si + 2FeO → SiO₂ + 2Fe. Qhov ceev ntawm SiO₂ generated yog 2.65 g / cm³, qis dua li cov hlau molten (7.1 g / cm³), ua rau nws yooj yim rau ntab thiab tsim slag.
Calcium- txhim kho deoxidation:
2 Ca + O₂ → 2CaO. Calcium muaj zog affinity rau oxygen dua silicon, uas tuaj yeem tshem tawm cov pa oxygen seem hauv cov hlau molten. Ib txhij, nws reacts nrog Al₂O₃ kom tsim tsawg- melting-point composite inclusions (CaO・Al₂O₃), pab kom sib cais.
(3) Grain Refinement: Refines lub microstructure, ntsuas lub zog thiab toughness.
Mechanism ntawm Action:
Cov me me (xws li CaS, SiO₂) hauv silicon -calcium alloys ua raws li qhov chaw nucleation heterogeneous, txhawb kev tsim cov nplej nplua nuj ntau dua li ob peb coarse nplej thaum lub sij hawm cam khwb cia hlau solidification.
Grain Boundary Strengthening:
Refined nplej nce tus naj npawb ntawm cov ciam teb ntawm ib chav tsev ntim, cuam tshuam kev txav mus los thiab cuam tshuam kev ntxhov siab, yog li txhim kho cov khoom siv tag nrho.
(4) Sulfur Control: Tshem Tawm Kub Brittleness thiab txhim kho Machining Performance
Mechanism ntawm Action:
Calcium preferentially reacts nrog sulfur: Ca + FeS → CaS + Fe. CaS muaj qhov melting point ntawm 2450 degree, yog insoluble nyob rau hauv molten hlau, precipitates raws li cov khoom, thiab floats mus rau lub slag, tag nrho tshem tawm cov teeb meem ntawm leej faj.
Tus nqi tseem ceeb:
Tiv thaiv FeS (melting point 1190 degree) los ntawm kev tsim ib qho kev sib txuas txuas ntxiv ntawm cov ciam teb nplej, tshem tawm qhov tshwm sim "kub brittleness".
Cov ntsiab lus tseem ceeb tswj kev siv:
Lub Sijhawm Ntxiv:Ntxiv rau cov hlau ductile tom qab spheroidizing kho thiab ua ntej inoculation; ntxiv rau grey cam khwb cia hlau 5-10 feeb ua ntej tapping kom paub meej txaus cov tshuaj tiv thaiv.
Txoj Kev Ntxiv:NtxivCaSi Lumpcov khoom ncaj qha; ntxivSiCa hmoovcov khoom los ntawm ib qho inoculator; ntxivCaSi cored hlaucov khoom siv cov khoom siv hlau (ceev 3-5 m / s) kom tsis txhob muaj calcium volatilization poob.
Dosage Control: Excessive addition (>0.5%) will lead to excessively high cast iron hardness (HB>250), nce kev ua haujlwm nyuaj. Precise tswj yuav tsum tau raws li hom cam khwb cia hlau.
