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Mechanism for corrosion protection of β-TCP reinforced ZK60 via laser rapid solidification

A B

C D

Figure 2. SEM of the ZK60/xβ-TCP composites: (A) dot like MgZn phase distributed in ZK60; (B) divorced slender
β-TCP phase uniformly distributed along grains boundaries in ZK60/4β-TCP; (C) continuous slender β-TCP phase in
ZK60/8β-TCP; (D) pores were observed in ZK60/12β-TCP.
β-TCP phase was observed uniformly distributing along ZK60, ZK60/4β-TCP and ZK60/8β-TCP (p > 0.05).
grains boundaries (Figure 2B). For ZK60/8β-TCP, more However, a considerable decrease of relative density
slender β-TCP phases homogeneously precipitated along to 88.5 ± 3.5% was observed with a further increase
the grain boundaries, compared with ZK60/4β-TCP of β-TCP to 12 wt. %. The significantly lower relative
(Figure 2C). While β-TCP content was up to 12 wt. %, density of ZK60/12β-TCP as compared with ZK60/8β-
the precipitated β-TCP was considerably coarsened and TCP indicated that the agglomeration of β-TCP particles
agglomerated, forming a continuous network structure. deteriorated the densification behavior of Mg matrix
Besides, some pores were observed in the matrix of during solidification.
ZK60/12β-TCP (Figure 2D). The obtained XRD patterns of β-TCP/ZK60 com-
The relative density of laser-melted ZK60/xβ-TCP posites were shown in Figure 4. Compared with the
composites was investigated, with results shown in ZK60, besides the diffraction peaks corresponding
Figure 3. Laser-melted ZK60 obtained a high level of to α-Mg, the diffraction peaks of β-TCP were also
relative density of 98.8 ± 0.6%. After composited with detected in the β-TCP/xZK60 composite. In addition, the
β-TCP, ZK60/4β-TCP and ZK60/8β-TCP still reached diffraction peaks of β-TCP became stronger with β-TCP
a high relative density of 97.6 ± 1.1% and 97.2 ± 1.8%, increasing. The XRD results also demonstrated that no
respectively, with no significant difference among other new phases formed, indicating that no chemical

Figure 3. The relative density of the ZK60/xβ-TCP composites. The insets were the corresponding optical images.

4 International Journal of Bioprinting (2018)–Volume 4, Issue 1