WE CLAIM
1. A method of depositing an abradable coating on a gas turbine engine component (10), comprising:
(a) forming a slurry mixture (100) comprising at least bi-modal ceramic particulate with up to about 70% by volume of coarse particulate wherein said coarse particulate is at least one of Ln2Si2O7, Ln2SiO5, silica, barium strontium aluminosilicate (BSAS), monoclinic hafnium oxide, rare earth gallium garnet (Ln2Ga2O9) where Ln is at least one of Scandium (Sc), Yttrium (Y), Lanthanum (La), Cerium (Ce), Phraseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolimium (Gd), Terbium (Tb), Dysprosium (Dy), Hlomium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), and up to about 60 % by volume of fine particulate, wherein said fine particulate includes at least one of Ln2Si2O7 or Ln2SiO5 where Ln is at least one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, a dispersant for said ceramic particulate, and a monomer solution, a free-radical initiator compound, a low vapor pressure organic solvent and at least one sinter aid selected from the group consisting of consisting of iron, aluminum, titanium, cobalt, nickel, gallium, tin, indium, any compounds thereof (e.g. oxides, acetates, oxalates, carbides, nitrides, carbonates, acetylacetonates, nitrates, silicides, any compounds containing a rare earth element, etc), mixtures thereof, or mixtures of compounds thereof;
(b) applying said slurry mixture to at least one of said gas turbine engine component (102) and a mold (104);
(c) gelling said slurry mixture (106) to polymerize and crosslink forming a firm irreversible gel matrix on said gas turbine component with said monomer solution and said free-radical initiator compound by heating said mold containing at least one of said gas turbine engine component and said slurry mixture to a first temperature between about 30° C - 80° C. before evaporation of said organic solvent;

(d) drying said irreversible gel matrix (108) at a second temperature of between 80° C. to 250° C. to effect a particulate on said gas turbine engine component one of within or removed from said mold; and,
(e) sintering said particulate of said dried irreversible gel matrix (110) on said gas turbine engine component at a temperature greater than about 1204° C and less than about 1357° C forming a layer of said coating having a thickness greater than about 6 mils and a porosity of about 5 percent to about 50 percent, wherein said sintered layer comprises a doped rare earth disilicate where the sintering aid is a doping composition that dissolves into, and dopes the rare earth disilicate.

2. The method of Claim 1, wherein said coating is a porous, continuous abradable.
3. The method of Claim 2, further comprising inhibiting breakage of an adjacent component upon engagement with said abradable coating.
4. The method of Claim 1, wherein said coating is a solid abradable.
5. The method of Claim 1, wherein said coating is formed with a pattern.
6. The method of Claim 1, wherein said bi-modal ceramic particulate improves evaporation and reduces stress resulting in a substantially crack-free coating.
7. The method of Claim 1, wherein said coating includes a hermetic coating (16).
8. The method of Claim 1, wherein said gas turbine engine component is one of a blade or a shroud.
9. The method of Claim 1, wherein said irreversible gel matrix inhibits separation of said bi-modal ceramic particulate.
10. The method of Claim 11, wherein said irreversible gel matrix inhibits settling of said coarse particulate.
11. A gas turbine engine component, comprising:
a ceramic matrix composite (CMC) part (12) forming one of a blade or shroud;
an environmental coating (14) on an outer surface of said CMC part;

an abradable coating (30, 130) disposed on said environmental barrier coating;
said abradable coating comprising:
a bi-modal particulate including up to 70 percent by volume of a coarse particulate and up to 60 percent by volume of a fine particulate;
a free-radical initiator compound;
a low vapor pressure organic solvent;
at least one sintering aid selected from the group consisting of a iron, aluminum, titanium, cobalt, nickel, gallium, tin, indium, any compounds thereof (e.g. oxides, acetates, oxalates, carbides, nitrides, carbonates, acetylacetonates, nitrates, silicides, any compounds containing a rare earth element), mixtures thereof, or mixtures of compounds thereof;
a gel-matrix spanning network formed by said bi-modal particulate being one of a monomer solution and polymer solution;
said gel matrix being dried and sintered on said CMC gas turbine engine component and having a thickness of at least about 5 mils.