A Study On Femtosecond Laser Sintering Metal Powder

The interaction between the femtosecond laser and the material has the characteristics of short duration and tiny thermal effect,which makes the femtosecond laser have an irreplaceable advantage in the field of precision machining.Femtosecond laser sintering of metal powder can obtain denser and harder bulk metal than continuous laser.In order to prevent oxidation,the sintering of the metal powder is usually carried out in protective gas.But protective gas could not always conveniently be used in some application scenario.To obtain the conditions of the non-oxidized region,the sintering of metal powder in an unprotected atmosphere was studied in this paper.Using the back-sintering and forward high-power sintering methods,all or part of the nonoxidized metal thin wires were obtained in the air,and the back-sintering method was used to fabracate terahertz polarization modulation devices.The main work of this paper includes the following two aspects:1,Femtosecond laser with repeatation frequency of 50 MHz was used to sinter tin paritical.The morphology and composition of the metal thin wires attached to the substrate were analyzed.The relationship between the line width and the processing parameters was summarized.Metal pellets were observed and its cause was analyzed.The elemental composition of the tin metal wire was analyzed and found no oxidation occurred during the processing.Eight sets of grating parameters were designed by using the relationship between processing parameters and metal line width.The devices used to modulate terahertz waves were tested.2,Femtosecond laser with repeatation frequency of 50 MHz was used to sinter iron paritical.The range of action was roughly divided into four regions.The width and Raman spectrum of each region were measured.The relationship between the width of the four regions and the laser power,scanning speed,and particle size was analyzed.The composition distribution of different regions was analyzed.There were no oxidation occurred in the thin metal wires in the central part,and a large range of oxidation occurred in the edge regions.The causes of the formation of various components in different regions were analyzed.