POROUS CERAMIC BASED ON CALCIUM PYROPHOSPHATE
T. F. Safronova,
V. I. Putlyaev,
Ya. Yu. Filippov,
D. S. Larionov,
P. V. Evdokimov,
A. E. Averina,
E. S. Klimashina,
and V. K. Ivanov
Translated from Novye Ogneupory, No. 1, pp. 46 – 51, January 2015.
Original article submitted September 8, 2014.
Porous ceramic, whose composition is mainly represented by calcium b-pyrophosphate b-Ca
pared from a porous mixture containing synthetic calcium g-pyrophosphate g-Ca
and milled 1-aqueous
sodium dihydrophosphate in an amount from 2.5 to 40 wt.%. Ceramic sintering proceeds by a liquid-phase
sintering mechanism due to melt formation in the system Na
. Ceramic microstructure after fir
ing in the range 800 – 1000°C makes it possible to consider sodium polyphosphate not only as a component
facilitating sintering by a liquid-phase mechanism, but also as an inorganic pore-forming agent.
Keywords: porous ceramic, calcium pyrophosphate, sodium dihydrophosphate, sodium polyphosphate, inor
ganic pore-forming agent.
Regenerative methods for treating bone defects suggest
use of porous resorbable biocompatible and bioactive raw
material. The phase composition of these materials should be
represented by biocompatible inorganic components with
predominance of biodegradable (resorbable) phase . Cal
cium phosphates with a ratio Ca/P < 1.5 are resorbable, i.e.,
capable of dissolving when implanted within a human organ
ism. Resorbable ceramic materials based on calcium phos
phate according to known phase diagrams may contain
phases of tricalcium phosphate Ca
, calcium pyrophos
(CPP), and calcium polyphosphate Ca(PO
Porous inorganic materials are used for preparing bone
implants, and in fact for treating small bone defects not expe
riencing mechanical loads. For effective intergrowth of bone
into an implant the latter should have a connected pore sys
tem with sizes not less than 100 mm. Material strength should
be adequate for a physician to perform necessary manipula
tion both in the stage of implant preparation and also during
an operation. This porous material, present in the area of a
bone defect, creates conditions for forming a composite arti-
ficial inorganic material, i.e., organic component, and then a
composite regenerated hydroxyl apatite carbonate as an or-
Various methods are used in order to prepare porous ma-
terials [2, 3]. Porous ceramic materials based on calcium
phosphates for medicine are prepared by duplication with a
polymer [4, 5] or inorganic  matrix. The porous polymer
matrix used is predominantly cellular polyurethane foam.
Porous materials based on calcium phosphates are prepared
using spheres of organic material  as burning-off or re
movable during heating: polystyrene latex, polymethyl
methacrylate, paraffin, polyethylene, etc. Removable pore-
forming agents also concern camphene , or water .
Molding from a foam slip is also used in order to prepare po
rous materials based on calcium phosphates .
A special group among methods for preparing porous in
organic materials is those using inorganic pore-forming
agents. This concerns carbonates, which are normally added
in an amount of 1 – 5%. Carbonates are capable of develop
ing properties of inorganic pore-forming agents in systems
within whose composition there are components forming a
melt on heating . Calcium carbonate, sodium carbonate,
sodium hydrocarbonate, ammonium hydrophosphate, and
potassium carbonate (from potassium acetate) [11, 12], are
used as inorganic pore-forming agents in preparing materials
for bone implants.
Refractories and Industrial Ceramics Vol. 56, No. 1, May, 2015
1083-4877/15/05601-0043 © 2015 Springer Science+Business Media New York
M. V. Lomonosov Moscow State University, Moscow, Russia.
M. V. Lomonosov Moscow State University, Materials Science
Faculty, Moscow, Russia.
FGBUN N. S. Kurnakov Institute of General and Inorganic
Chemistry, Russian Academy of Sciences, Moscow, Russia.