*3.2.1 Composite foams/foams with guest phases with preload of new phases in the preform*

Loading of new phases is achieved by one of the following two strategies: (i) loading particles (inclusions) are packed together with larger martyr particles forming a porous bimodal preform, or (ii) loading particles are covered by a martyr material and packed forming a porous monomodal preform. Preforms are infiltrated and the martyr material is leached away. As a result, composite foams or foams with guest phases are obtained. They show homogeneous dispersion of new phases in a continuous matrix. **Figure 2** represents the aforementioned material structures. In particular cases, loading powders are packed combined with larger martyr particles and sintered. The martyr particles are later removed to obtain an interconnected porous structure.

### *3.2.2 Composite foams with preload of new phases in the liquid precursor*

Loading of new phases is achieved by the dispersion of particles into the liquid precursor. The preform is leached away after its infiltration with the liquid precursor, and the final material shows a homogeneous dispersion of new phases in a continuous matrix. Material consolidation can also be obtained (instead of by infiltration) by electrochemical (co)-deposition of a metal and/or the new phases on a leachable preform or a preexistent porous material (the liquid precursor is an electrolyte that contains metal ions and dispersed particles of the new phases) (**Figure 3**).

*Foams - Emerging Technologies*

cal infections [15, 16].

soaked.

**3. Manufacture**

**3.1 Manufacturing techniques of open-pore foams**

a.Investment casting with polymer foams

a.Partial sintering of powders and fibers

important processing techniques are:

techniques are the most important ones:

d.Sintering of hollow spheres

e. Sintering of powders and binders

f. Reaction sintering of multicomponent systems

g.Vapor deposition onto polymeric foams

h.Electrodeposition onto polymeric foams

b.Foaming of slurries

**Vapor state processing**:

**Ionic solution state processing**:

materials are not only intended to fulfill a structural purpose in a body system but also to cover functional applications. It was recently proposed to incorporate guest phases in the porous cavities of open-pore foams charged with pharmacological substances, with the aim to set a drug delivery system to avoid postsurgi-

By way of the commented examples, the authors intend to highlight that the inclusion of new phases into open-pore foams opens up a range of new properties in foam materials and seems to be a suitable way to overcome the requirements of modern applications such as some of those commented for thermal management, catalytic chemistry, and medical implantology. In addition, some research works focus on the incorporation of new phases into foams to enhance mechanical properties as in all the mentioned applications, better mechanical performances are also

Manufacturing techniques of open-pore foams can be classified into four groups attending to the state of the precursor material: liquid, solid, vapor, and ions [1]. **Liquid state processing**: the precursor material is in liquid state. The most

b.Casting around space holder materials/infiltration of martyr preforms

**Solid state processing**: the precursor material is in solid state. The following

Despite the wide range of fabrication methods that these four groups generate,

there are actually only two different strategies for generating porosity [17]:

c.Pressurization and sintering of powders in martyr preform

**4**


*Methods currently developed to manufacture multiphase open-pore foams.*

**7**

*3.2.3 Finned foams*

*components joining (b) for finned foams.*

**Figure 4.**

*Open-Pore Foams Modified by Incorporation of New Phases: Multiphase Foams for Thermal…*

(a) (b) (c) (d)

*Schematic drawings showing preform compositions (a and c) and the structures of the final materials (b and d) for composite foams (a and b) and foams with guest phases (c and d) obtained by preload of new phases in* 

*Schematic drawings showing preform compositions (a and c) and the structures of the final materials (b and d) for composite foams obtained by preload of new phases in the liquid precursor processed by infiltration* 

Finned foams are normally manufactured by physical bonding or by gluing preexistent monolith layers (herein called components) of porous and nonporous materials. The nonporous materials are considered the new phases which are

*Schematic drawings showing component composition (a) and the structure of the final material after* 

*DOI: http://dx.doi.org/10.5772/intechopen.88977*

*(a and b) or by electrochemical (co)-deposition (c and d).*

**Figure 2.**

*the preform.*

**Figure 3.**

*Foams - Emerging Technologies*

**6**

*Open-Pore Foams Modified by Incorporation of New Phases: Multiphase Foams for Thermal… DOI: http://dx.doi.org/10.5772/intechopen.88977*

**Figure 2.**

*Foams - Emerging Technologies*

**6**

**Method** **Material type**

New phase

loading

Distribution of

Homogeneous dispersion in

Homogeneous dispersion in

Homogeneous dispersion

Homogeneous dispersion

Homogeneous dispersion

in one component; layered

distribution of components

Combination of packed/selfstanding preforms with liquid

precursor

Continuous

in one component; layered

distribution of components

Casting of liquid precursor

in a mold

in one component; layered

distribution of components

Physical or glue joining

of preexistent monolithic

materials

Noncontinuous

Continuous

matrix and/or pore surface

new phases

Assembly

Combination of packed/

Combination of packed/selfstanding preforms with liquid

precursor/electrodeposition

Continuous

self-standing preforms with

liquid precursor or powders

Matrix

Continuous

continuity

References

**Table 1.**

*Methods currently developed to manufacture multiphase open-pore foams.*

[8, 13, 15, 16, 19]

[8, 14, 20–29]

[30–32]

[33]

[13]

matrix

**Composite foams/foams** 

**Composite foams**

**Finned foams**

**Monolithic finned foams**

**Composite finned foams**

**with guest phases**

Preload in preform

Preload in liquid precursor

No preload

No preload

Preload in preform

**Inclusion into monolithic materials**

**Combination of monolithic materials**

*Schematic drawings showing preform compositions (a and c) and the structures of the final materials (b and d) for composite foams (a and b) and foams with guest phases (c and d) obtained by preload of new phases in the preform.*

### **Figure 3.**

*Schematic drawings showing preform compositions (a and c) and the structures of the final materials (b and d) for composite foams obtained by preload of new phases in the liquid precursor processed by infiltration (a and b) or by electrochemical (co)-deposition (c and d).*

### **Figure 4.**

*Schematic drawings showing component composition (a) and the structure of the final material after components joining (b) for finned foams.*

### *3.2.3 Finned foams*

Finned foams are normally manufactured by physical bonding or by gluing preexistent monolith layers (herein called components) of porous and nonporous materials. The nonporous materials are considered the new phases which are

integrated into a material with a layered structure and a noncontinuous matrix (joints are present in between components) (**Figure 4**).
