TY  - JOUR
A1  - Boehm, Anne
A1  - Meininger, Susanne
A1  - Tesch, Annemarie
A1  - Gbureck, Uwe
A1  - Müller, Frank A.
T1  - The mechanical properties of biocompatible apatite bone cement reinforced with chemically activated carbon fibers
JF  - Materials
N2  - Calcium phosphate cement (CPC) is a well-established bone replacement material in dentistry and orthopedics. CPC mimics the physicochemical properties of natural bone and therefore shows excellent in vivo behavior. However, due to their brittleness, the application of CPC implants is limited to non-load bearing areas. Generally, the fiber-reinforcement of ceramic materials enhances fracture resistance, but simultaneously reduces the strength of the composite. Combining strong C-fiber reinforcement with a hydroxyapatite to form a CPC with a chemical modification of the fiber surface allowed us to adjust the fiber–matrix interface and consequently the fracture behavior. Thus, we could demonstrate enhanced mechanical properties of CPC in terms of bending strength and work of fracture to a strain of 5% (WOF5). Hereby, the strength increased by a factor of four from 9.2 ± 1.7 to 38.4 ± 1.7 MPa. Simultaneously, the WOF5 increased from 0.02 ± 0.004 to 2.0 ± 0.6 kJ∙m−2, when utilizing an aqua regia/CaCl2 pretreatment. The cell proliferation and activity of MG63 osteoblast-like cells as biocompatibility markers were not affected by fiber addition nor by fiber treatment. CPC reinforced with chemically activated C-fibers is a promising bone replacement material for load-bearing applications.
KW  - calcium phosphate cement
KW  - damage tolerant cement
KW  - carbon fiber reinforcement
KW  - interface control
KW  - fiber–matrix interaction
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197808
SN  - 1996-1944
VL  - 11
IS  - 2
ER  - 
TY  - JOUR
A1  - Seifert, Annika
A1  - Groll, Jürgen
A1  - Weichhold, Jan
A1  - Boehm, Anne V.
A1  - Müller, Frank A.
A1  - Gbureck, Uwe
T1  - Phase Conversion of Ice‐Templated α‐Tricalcium Phosphate Scaffolds into Low‐Temperature Calcium Phosphates with Anisotropic Open Porosity
JF  - Advanced Engineering Materials
N2  - The current study aims to extend the material platform for anisotropically structured calcium phosphates to low-temperature phases such as calcium-deficient hydroxyapatite (CDHA) or the secondary phosphates monetite and brushite. This is achieved by the phase conversion of highly porous α-tricalcium phosphate (α-TCP) scaffolds fabricated by ice-templating into the aforementioned phases by hydrothermal treatment or incubation in phosphoric acid. Prior to these steps, α-TCP scaffolds are either sintered for 8 h at 1400 °C or remain in their original state. Both nonsintered and sintered α-TCP specimens are converted into CDHA by hydrothermal treatment, while a transformation into monetite and brushite is achieved by incubation in phosphoric acid. Hydrothermal treatment for 72 h at 175 °C increases the porosity in nonsintered samples from 85% to 88% and from 75% to 88% in the sintered ones. An increase in the specific surface area from (1.102 ± 0.005) to (9.17 ± 0.01) m2 g−1 and from (0.190 ± 0.004) to (2.809 ± 0.002) m2 g−1 due to the phase conversion is visible for both the nonsintered and sintered samples. Compressive strength of the nonsintered samples increases significantly from (0.76 ± 0.11) to (5.29 ± 0.94) MPa due to incubation in phosphoric acid.
KW  - phase conversion
KW  - α-tricalcium phosphate
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256311
VL  - 23
IS  - 5
ER  -