Wavelength conversion element, light source device, projector, and method of manufacturing wavelength conversion element

A method of manufacturing a wavelength conversion element, the method comprising:

• a preparation step of preparing a mixture obtained by mixing phosphor particles and a binder including glass with each other;
• a coating step of applying the mixture on a holding member including alumina;
• and
• a calcination step of calcining the mixture, wherein
• a calcination temperature in the calcination step is 100° C. or more higher than a softening point of the glass,
• the holding member is provided with a pore,
• defining an apparent porosity of the holding member as X expressed in terms of %,
• defining bending strength of the holding member as A expressed in terms of MPa, A fulfills a formula (3) below,
• defining an elastic modulus of the holding member as B expressed in terms of GPa, B fulfills a formula (4) below, and
• defining an elastic modulus of the glass as C expressed in terms of GPa,
• defining a sum of a reciprocal of B and a reciprocal of C as D,
• defining a product of a difference between a linear expansion coefficient of the holding member and a linear expansion coefficient of the glass and a transition point of the glass as Y,
• a value of Y is smaller than a value of a product of A, D, and 0.001 when the linear expansion coefficient of the glass is smaller than the linear expansion coefficient of the holding member in a temperature range from the transition point of the glass to a room temperature
• A=−7.11X+316.52 (3)
• B=−6.26X+288.43 (4).

A method of manufacturing a wavelength conversion element, the method comprising:

• a preparation step of preparing a mixture obtained by mixing phosphor particles and a binder including glass with each other;
• a coating step of applying the mixture on a holding member including alumina;
• and
• a calcination step of calcining the mixture, wherein
• viscosity of the glass in the calcination step is no higher than 106 dPa·s,
• the holding member is provided with a pore,
• defining an apparent porosity of the holding member as X expressed in terms of %,
• defining bending strength of the holding member as A expressed in terms of MPa, A fulfills a formula (5) below,
• defining an elastic modulus of the holding member as B expressed in terms of GPa, B fulfills a formula (6) below, and
• defining an elastic modulus of the glass as C expressed in terms of GPa,
• defining a sum of a reciprocal of B and a reciprocal of C as D,
• defining a product of a difference between a linear expansion coefficient of the holding member and a linear expansion coefficient of the glass and a transition point of the glass as Y,
• a value of Y is smaller than a value of a product of A, D, and 0.001 when the linear expansion coefficient of the glass is smaller than the linear expansion coefficient of the holding member in a temperature range from the transition point of the glass to a room temperature
• A=−7.11X+316.52 (5)
• B=−6.26X+288.43 (6).