alumina material was reinforced with thermoplastic polymer (poly-methyl methacrylate pmma)
by infiltration method in this study. where pure alumina (?-al2o3) powder was mixed with
naphthalene as volatile material by weight fractions of naphthalene (0,15,30,45) wt% for a period of 3
hours by electric mixer to prepared the porous ceramic material. specimens were prepared by pressing
after added (pva) binder. they were dried at (110 ) and sintered at (1000 ) and stay for 1 hour at
that temperature. then, the physical properties such as porosity, density and the mechanical properties
such as compressive, impact strength were measured before infiltration.
infiltration material (poly-methyl methacrylate pmma) was prepared by mixing (83%) of
chloroform as solvent material to granules pmma and heating at (50 ) with movement to convert
that mixture into a liquid material with less viscosity. after that the samples was immersed in liquid
(infiltration material) and left to allow the volatile material (chloroform) to escape by evaporation
leaving pmma alone as reinforcement materials. then, mechanical and physical properties of the
samples were tested after infiltration process. the results showed an improvement their physical and
mechanical properties of the composite material.

2-experimental
2.1 samples preparation
the present study was achieved by taking basic material as a matrix of pure
alumina (?-al2o3), figure (1) referred to alumina powder analysis by x-ray
diffraction. figure (2) referred to particle size analysis by (bettersize2000 laser
particle size analyzer) of alumina powder, particle size of alumina was (1.184 ?m) as
shown in figure (2). samples were achieved by pressing, draying, sintering, and
reinforced by thermoplastic polymer pmma (poly-methyl methacrylate) as will be
seen later.
the samples were prepared as following firstly, four quantity of alumina powder
and naphthalene powder were mixed in order to obtain porosity material of alumina.
respectively, was included weight fractions (0,15, 30 and 45 wt. %) of naphthalene,
the mixture were mixed by an electric mixer for 4 hours for each case. then to obtain
samples with suitable strength a load of 12 kn was chosen to press the samples after
using polymer binders (e.g. pva). the addition of pva was achieved by added two
dropings into alumina powder of each sample. however, dimension of samples were
achieved according to the astm for compression (c773-88) and impact (c368-88).
the infiltration material was prepared by mixing pmma with 83% chloroform
(e.g. 17% polymer) to make infiltration mixture. the mixture was treated in glass

beaker and mixed by magnetic stirrer with heating at (50 0c) to reduce viscosity of
pmma.
2.2 drying and sintering
the samples were dried at (110 0c) for 24 hours, as well as sintering the samples at
(1000 0c) with heating rate 5 degree for 1 minute to prevent distortion of the samples
and they was still at these degrees for a period of 1 hour. so that left them inside oven
to 24 hours to reach at room temperature to be ready for testing the physical and
mechanical properties before infiltration processes.
2.3 physical and mechanical testing
2.3.1 physical test
the porosity and bulk density was carried out before and after infiltration
processing. the porosity test and the apparent density (g/cm3) test were achieved
according astm standard (c373-88) as following.
a- apparent porosity
the samples were dried at (1100c for 24 hours.) and left in an oven to cool until
room temperature and measured dry weight (wdry). samples was boiled in distilled
water for (5 hr.), and left to be submerged inside distilled water for (24 hours.) and the
submerged weight (wsub.) was then measured. lastly samples was dried by a cloth and
then taken the submerged weight (wsat.), then apply the porosity eq. (frank et.
al.,1998).
apparent porosity = (wsat- wdry. / wsat- wsub) %
b- bulk density
to conduct density test, the exterior volume eq. (waffa, 1999) is applied.
ve= (wsat- wsub)/
since pw (water density)=1(g/cm3) and
bulk density = wdry / ve . (gacek et. al., 1981)
2.3.2 mechanical test
mechanical testing was carried out to check strength of samples before and after
infiltration as follows
a- compressive strength test
the compressive strength was calculated according to astm standard (c 773-88).
the samples were cylindrical with dimension (d=10 mm, h=20 mm). the change
after infiltration was calculated with the following compressive strength equation
compressive strength= p/a (mpa), (lahaska et. al., 1987), since p: is a load (n), a:
sectional area (mm2).
b-impact strength test
the impact strength, by (charpy method), was performed according to astm
standard (c368-88). the samples were blocks like square section with dimension
(l=55mm, w=10mm, h=10 mm). the change after infiltration was calculated with
the following equation
impact strength=w/a (kj/m2). (subramanian et. al., 1998).
since w: is break energy (j), a: sectional area (mm2).
3-results and discussion
the test results showed improvement in physical and mechanical properties of
ceramic composite were apparent in figures (3,4,5 and 6). figure (3) referred to
change in porosity before and after infiltration process. the porosity was increase
before infiltration process and decreased after infiltration process due to filling the
pores with pmma substance.
figure (4) showed change in bulk density before and after infiltration process
though the change was little. the reason of composite density increase after

infiltration was due to density of pmma as reinforcement material which added by
infiltration process. but before infiltration the porosity was increase that due to lack in
density as known fact (ahmed et. al.,2004).
in figure (5) referred to effect of infiltration process on compressive strength.
there was a reduction of compressive strength before infiltration but there was
improvement in compressive strength of composite after filling of pores. so that the
samples with less pores showed higher compressive strength than the other ones with
increase of porosity (patankar et. al., 1998 ).
the test of impact strength aimed to calculate the substance toughness and ability to
energy absorption till fracture, figure (6) was indicated to result of impact strength.
the improvement in mechanical properties was clear because disappearance of the
crack (singer et. al., 1963) after filling of pores. also the improvement in impact
strength of samples was due to infiltration with less porosity and strength of
reinforcement material.
4-conclusion
1-the samples showed a difference of porosity with different compactions, and the
high porosity showed weakness in strength.
2-the using of heating with mixing chloroform and pmma will be better to reduce
high viscosity of polymer.
3-the impact strength of brittle materials can be improved with additive polymer
materials.
4-the results refer to the porosity causes reduced of mechanical properties such as
impact, compressive strength.
5-small pores can improve compressive, impact strength and this shows that the small
pores absorb polymer more than the large pores do.